Human monoclonal antibodies and methods for producing the same

ABSTRACT

The present invention provides for methods of producing human monoclonal antibodies against a wide variety of antigens including bacterial and viral antigens, as well as tumor antigens, and various autoantigens. Also provided are the antibodies themselves, nucleic acids encoding such antibodies, cells producing such antibodies, and methods of using such antibodies for diagnostic assays and passive immunity against disease states such as infection and cancer.

This invention was made with government support under grant number 5K01CA095443 awarded by the National Cancer Institute, National Institute of Health. The government has certain rights in the invention.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national phase application under 35 U.S.C. §371 of International Application No. PCT/US2008/072124, filed Aug. 4, 2008, which claims the priority of U.S. Provisional Patent Application Ser. No. 60/953,739, filed Aug. 3, 2007, the entire disclosures of which are specifically incorporated herein by reference.

REFERENCE TO A SEQUENCE LISTING SUBMITTED ELECTRONICALLY

The content of the electronically submitted sequence listing (“205350_(—)0002_(—)494617.txt”, 38,573 bytes, created on Nov. 22, 2013) filed with this application is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

I. Field of the Invention

The present invention relates generally to the fields of cell biology and immunology. More particularly, it concerns methods and compositions relating to the production of human monoclonal antibodies.

II. Description of Related Art

Current alternatives to vaccination are therapies consisting of antibiotics, antivirals or the passive transfer of antibodies, which are blood derived proteins that bind and neutralize pathogens. The source of antibodies may be a polyclonal supply, such as human or horse serum, or derived from a monoclonal source (single cell clone). With the technologic capability to control and select for specific antigen binding, monoclonal antibodies have yielded dramatic therapeutic benefits in cancer treatment worldwide. While some success in the treatment of infectious agents and toxins has also been observed with monoclonals, the potential for therapeutic and diagnostic agents remains largely untapped.

One particular impediment to the development of monoclonal antibodies for human therapy is the need to “humanize” such antibodies, which are generally made in mice, rats and rabbits. If human patients are administered such antibodies without humanized constant regions, they can suffer from “serum sickness,” literally meaning that an antibody is mounted by the recipient against the non-human antibody sequences. While humanizing monoclonal antibodies produced in research animals can avoid this problem, this does not come without a cost—both time and expense for humanization of antibodies are considerable, leading to a bottleneck when it comes to exploiting the use of monoclonal antibodies for therapy and diagnosis in humans.

SUMMARY OF THE INVENTION

Thus, in accordance with the present invention, there is provided a method of producing an immortalized human B-cell secreting an antibody specific for a predetermined antigen comprising (a) obtaining a population of IgM-positive human B-cells; (b) contacting said population with (i) Epstein-Barr virus (EBV) to immortalize said human B-cells, and (ii) a cytokine/growth factor/signaling agent cocktail to induce B-cell differentiation, resulting in IgM-to-IgG immunoglobulin isotype class-switching and immunoglobulin secretion; and (c) culturing cells under conditions supporting said immortalization, differentiation, immunoglobulin isotype class-switching and secretion. The method may further comprise (d) selecting an immortalized human B-cell expressing an antibody for a pre-determined antigen. The selecting step may comprise an immunoassay performed on immortalized B-cell culture medium supernatants. The method may further comprise isolating a nucleic acid encoding an entire heavy and/or light chain from the immortalized human B-cell of step (d), or further comprise isolating a nucleic acid encoding a heavy and/or light chain antigen-binding region from the immortalized human B-cell of step (d), and may even further comprise cloning said nucleic acid into a nucleic acid encoding a framework region of a heavy and/or light chain. Step (d) may occur after thawing stored frozen immortalized B-cells, and/or after thawing stored frozen culture medium supernatants from said immortalized B-cells. The B-cell may be antigen naïve or antigen experienced.

The predetermined antigen may comprise a viral antigen, a bacterial antigen, a fungal antigen, a parasite antigen, a toxin antigen, a cellular receptor antigen for virus entry, a cellular receptor for bacterial entry, a cellular receptor for fungus entry, a cellular receptor mediating parasite entry, a cellular receptor mediating toxin entry, a tumor antigen, a cytokine/chemokine/growth factor antigen, a cytokine/chemokine/growth factor receptor antigen, an antigen on molecules mediating inflammation, an antigen on molecules mediating pain, an antigen on molecules mediating tissue injury/damage, an antigen on activation molecules/ligands/receptors, an antigen on costimulatory molecules/ligands/receptors, an antigen on molecules mediating innate immunity, an antigen on cellular adhesion molecules, an antigen on cellular adhesion molecule receptors, an antigen on over-expressed/under-glycosylated/oxidized/misfolded/mutated cellular proteins (“altered self” antigens) associated with a disease state, an antigen on molecules/ligands/receptors mediating cell apoptosis, or an antigen on growth inhibitory molecules.

The cytokine/signaling agent cocktail may comprise anti-IgM F(ab′)₂ or other agents that crosslink or activate the B-cell receptor, recombinant human interleukin (IL)-2, IL-4, IL-5, IL-6, IL-9, IL-10, IL-13, interferon-α (IFN)-α, BAFF, and/or other cytokines that cause B-cell differentiation, and/or soluble CD40L, and/or other agents that supply a costimulatory signal to human B-cells. The population may be obtained from peripheral blood, tonsils, bone marrow, spleen, lymph nodes, umbilical cord blood, liver, apheresis procedures, and/or buffy coats.

The method in step (b) may further comprise an EBV concentration step, a centrifugation step during infection, or both. The method may further comprise freezing said population of human B-cells following step (c). Step (b)(ii) may be performed at about 0-96 hours following step (b)(ii), or at about 16-20 hours following step (b)(ii). About 50%-99%, or 90%-99% of said population may be immortalized by EBV infection. Step (d) may occur 1-4 weeks following infection, or 2-3 weeks following infection.

In another embodiment, there is provided an immortalized human B-cell expressing an IgG that binds immunologically to anthrax toxin, an Ebola virus antigen, ricin A chain, an A chain, a Yersinia pestis antigen, a Marburg virus antigen, a MDR Staphylococcus antigen, cholera toxin, a herpes B virus antigen, a hemorrhagic fever virus antigen.

Other embodiments provide for therapeutic human monoclonal antibodies specific for H5 hemagglutinin of avian influenza, an emerging infectious disease (SEQ ID NOS: 16 and 17). In some embodiments, the monoclonal antibodies have specificity for cancer angiogenic molecule placenta induced growth factor (PLGF), cancer and autoimmunity associated factor interleukin-6 (IL6), and toxins Staphylococcal enterotoxins B and C2 (SEB and SEC2, respectively), and ricin subunit B (the cell binding domain).

It is contemplated that any method or composition described herein can be implemented with respect to any other method or composition described herein.

The use of the word “a” or “an” when used in conjunction with the term “comprising” in the claims and/or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.” “About” is defined as including amounts varying from those stated by 5-10%.

These, and other, embodiments of the invention will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following description, while indicating various embodiments of the invention and numerous specific details thereof, is given by way of illustration and not of limitation. Many substitutions, modifications, additions and/or rearrangements may be made within the scope of the invention without departing from the spirit thereof, and the invention includes all such substitutions, modifications, additions and/or rearrangements.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings form part of the present specification and are included to further demonstrate certain aspects of the present invention. The invention may be better understood by reference to one or more of these drawings in combination with the detailed description of specific embodiments presented herein.

FIGS. 1A-B. Effect of TLR ligands and viral stock concentration on EBV infection efficiency. Primary tonsil B cells (10⁶ cells/ml/well were seeded in 24-well plate and infected with 1 ml of concentrated or un-concentrated B95-8 viral stocks from several different preparations, with the addition of various TLR ligands as indicated (see Example 1). After a 4 hr incubation, cells were dispensed into a 96-well plate using a 2-fold serial dilutions, starting at 5×10⁴ cells/well and ending with 24 cells/well. LCLs were scored visually by phase contrast microscopy 9 days post-infection. % immortalization efficiency was calculated as described in Example 1. Means±SD are shown (n=3). FIG. 1A. Effect of TLR ligands and viral preparation. FIG. 1B. Effect of virus stock concentration.

FIGS. 2A-C. Effect of EBV concentration and spinfection on Q293A infection efficiency. Q293A cells were trypsinized, counted and seeded at 1×10⁶ cells/1 ml/well into 6-well plates, and 1 ml of EBfaV-GFP stock, concentrated or un-concentrated, was added to the cells. Plates were (FIG. 2A) incubated overnight with un-concentrated EBfaV-GFP, (FIG. 2B) incubated overnight with concentrated EBfaV-GFP for inoculation or (FIG. 2C) centrifuged for 1 hour at 900 G for spinfection. EGFP fluorescence was detected with inverted microscope 48 hr post-infection.

FIGS. 3A-B. Efficient infection of primary tonsil B cells with EBfaV-GFP. B cells (2×10⁵ cells/0.1 ml/well) were seeded into wells of 96-well plate, mixed with 0.1 ml of 10-fold concentrated EBfaV-GFP and “spinfected” or “spinoculated” at 900 G for 1 hour. Similar number of cells was infected with B95-8 as a negative fluorescence control. Infection was evaluated 24 hours later, either as (FIG. 3A) visual evaluation of infection efficiency with fluorescent microscope; or (FIG. 3B) a flow cytometry analysis of infection. Gate indicates that 45% of cells fluoresce above background with a mean fluorescence intensity (MFI) of 15.1 for B95-8 infected cells in grey peak, and of 61.9 for EBfaV-GFP infected cells in green peak.

FIG. 4. IgG and IgM secretion profiles of B-cells from three tonsil samples treated for 1 week with different signaling agents. Tonsil B cells from 3 separate samples were prepared, inoculated with B95-8, seeded into 24-well plates, and treated with indicated signaling agents and cytokine combinations as described in Example 1. Culture supernatants were collected one week post-infection, and analyzed by ELISA for IgG and IgM levels as described in Example 1. Means±SD of samples and controls (n=4) are shown.

FIGS. 5A-B. IgM and IgG expression profile after at least 8 weeks in culture of representative samples following treatment with different signaling agent combinations. B cells from three tonsil samples were isolated, inoculated with B95-8 EBV, seeded into 24-well plates, and treated with the indicated combinations of signaling agents as described in Example 1. Cells were treated once a week for the first 3 weeks, and the culture supernatants were collected weekly. Culture supernatants collected on week 8 or week 10 post-infection were analyzed by ELISA for IgG and IgM levels as described in Example 1. Two representative specimens are shown in (FIG. 5A) that switched from IgM (white bars) to IgG (blue bars) secretion after continued culture with soluble CD40L, or IL-6 and anti-IgM(Fab′)₂, but not with IL-4 and anti-IgM(Fab′)₂ or without addition of cytokines (Media). The IgM and IgG secretion profiles for these same specimens cultured for only one week, at which time mainly IgM was produced, were shown in FIG. 4. (FIG. 5B) depicts representative results from a tonsil specimen that switched from IgM to IgG secretion after culture with BAFF, soluble CD40L and anti-IgM(Fab′)2. Again immunoglobulin isotype class switching did not occur after treatment with IL-4 and anti-IgM(Fab′)₂, or with media only. Means±SD of samples and controls (n=4) are shown.

FIGS. 6A-B. Immortalized B cells cultured with anti-IgM(Fab′)₂ and IL4 or IL6 differentiated into early plasma-like stage in vitro. Expression of indicated B-cell surface markers (role of which is summarized in Table 5) was evaluated by flow cytometry (see Example 1) on (FIG. 6A) primary tonsil B cells (green) and (FIG. 6B) immortalized B cells cultured for 19 weeks with either anti-IgM(Fab′)₂ and IL4, which secrete high IgM levels (red), or anti-IgM(Fab′)₂ and IL6, which secrete high IgG levels (blue).

FIG. 7. H5 HA-reactive antibodies are present in human sera from individuals never exposed to H5N1 avian influenza. Rituxan and purified human IgG were diluted to 5 mg/ml, while human sera were diluted 1:1000 in complete RPMI media. Samples or controls 0.1 ml per well were added in triplicate to ELISA plates previously coated with recombinant H5 HA, or to uncoated control wells. Plates were washed, blocked and probed with anti-human IgG as described in the methods (see Example 1). H5 HA coated plates were prepared by overnight incubation with recombinant protein diluted to 2 μg/ml in binding buffer, 0.1 ml per well. To help control for background non-specific binding, each sample was added to an equal number of control uncoated wells, receiving binding buffer only. Specific IgG binding to H5 HA was calculated by subtracting out the values obtained from background binding to the control uncoated wells; mean absorbance at OD₄₀₅±SD of samples and controls are shown (blue bars).

FIG. 8. Immortalized peripheral blood B cells obtained from volunteer V-5 (PBMC A1) were stimulated to produce IgG that binds H5N1 hemagglutinin (H5 HA). EBV-immortalized B cells derived from PBMC A1 sample were stimulated to produce IgG by treatment with anti-human IgM(Fab′)₂, IL-4, IL-6 and BAFF (see Example 1), and cultured in three 96-well plates (10⁴ cells per well). After week 1 (blue bars) and week 2 (red bars), culture supernatants from all wells on each plate were collected and pooled, then tested for H5 HA binding as described in Example 1. Mean absorbance at OD₄₀₅±SD of samples and controls (n=3) are shown.

FIG. 9. H5 HA specific IgG production in individual rows on plates identified with binding activity, from PBMC A1 sample. Culture supernatants from all wells in each row of reactive plates 1, 2 and 3 were pooled and assayed for H5 HA binding as described in the Example 1. Mean absorbance at OD₄₀₅±SD of samples and controls (n=3) are shown. Rows with significant H5 HA binding (Plate 1 row E, Plate 2, rows C, D and E, Plate 3, row D) were chosen for subsequent analysis.

FIG. 10. H5 HA specific IgG production in adjacent paired wells of rows identified with binding activity, from PBMC A1 sample. Week 3 culture supernatant from pairs of adjacent wells in H5 HA reactive rows (identified in FIG. 9) were pooled and assayed for H5 HA binding as described in Example 1. Mean absorbance at OD₄₀₅±SD of samples and controls (n=3) are shown. Wells 11 and 12 on plate 2 row D were selected for individual analysis.

FIG. 11. H5 HA specific IgG production localized to plate 2 well D11, from PBMC A1 sample. Culture supernatants from individual wells on plate 2, D11 and D12, were assayed for H5 HA binding as described in Example 1. Mean absorbance±SD of samples and controls (n=3) are shown. H5 HA reactivity at a level similar to that found in human serum controls was observed in well D11; cells from this well were chosen for subcloning.

FIG. 12. Subcloning strategy of H5 HA specific B cells found in plate 2 well D11, from PBMC A1 sample. EBV-immortalized B cells from PBMC A1 were stimulated to produce IgG with IL-4, IL-6, BAFF and anti-human IgM (Fab′)₂ (see Example 1), and cultured in three 96-well plates (10⁴ cells per well). H5 HA binding was determined as described in Example 1. Culture supernatants from all wells on each plate were collected (150 μl per well), and 50 μl per well were pooled and assayed for H5 HA binding. All plates contained H5 HA-reactive IgG after two weeks and culture supernatant from individual rows on these plates were pooled and assayed on week 3. Plate 1 row E, Plate 2 rows C, D and E, and Plate 3 row D had significant H5 HA binding. Culture supernatants from dual adjacent wells on each reactive row were assayed on week 4, identifying wells 5 and 6 on Plate 1, row E, and wells 11 and 12, on Plate 2, row D as having H5 HA binding. On week 5, reactive well D11 on Plate 2 was identified in a similar manner, and cells from this well were subcloned by limiting dilution analysis in 96-well plates containing 1, 10, 100, or 1000 cells per well. At weekly intervals thereafter, culture supernatants from all wells on each plate were pooled and tested by ELISA for H5 HA binding. Identification of a potentially clonal population secreting IgG reactive with H5 HA was isolated from well D11 of the plate containing 1 cell per well on week 8. The isolation strategy is summarized.

FIG. 13. Subcloning strategy for isolation of H5 HA specific B cell clones from PBMC A2 sample. EBV-immortalized B cells from PBMC A2 were stimulated to produce IgG by treatment with anti-human IgM(Fab′)₂, CD40L and BAFF (see Example 1), and cultured in six 96-well plates (10⁴ cells per well). H5 HA binding was determined as described in Example 1. Culture supernatants from all wells on each plate were collected (150 μl per well), and 50 μl per well were pooled and assayed for H5 HA binding. Plate 4, 5 and 6 were reactive with H5 HA, and culture supernatants from wells in each row on these plates were pooled and assayed (week 2). Supernatants in dual adjacent wells from reactive rows D and G on plate 4, row E on Plate 5 and row C on Plate 6 were collected and analyzed for H5 HA reactivity (week 3). The reactive wells G8 on Plate 4, E1 on Plate 5 and C3 on Plate 6 were subcloned by limiting dilution analysis in 96-well plates containing 1, 10, 100, or 1000 cells per well on week 4. Culture supernatant from all wells on each plate were pooled and tested by ELISA for H5 HA reactivity, identifying potential clonal populations on cells subcloned from Plate 4 and Plate 6 after 8-9 weeks.

FIG. 14. Lack of H5 HA specific IgG in culture supernatants derived from immortalized B cells from PBMC B sample. EBV-immortalized B cells from PBMC B were stimulated to produce IgG with IL-4, IL-6, BAFF and anti-human IgM (Fab′)₂ (see Example 1), and cultured in three 96-well plates (<10⁴ cells per well). H5 HA binding was determined as described in Example 1. Culture supernatants from all wells on each plate (150 μl per well) were collected, and 50 μl per well were pooled and assayed for H5 HA binding. This was repeated for three consecutive weeks without significant detection of H5 HA reactivity, at which point screening was discontinued.

FIG. 15. H5 HA specific IgG in culture supernatants from immortalized B cells, from TNSL A sample. EBV-immortalized B cells from TNSL A were stimulated to produce IgG with IL-4, IL-6, BAFF and anti-human IgM (Fab′)₂ (see Example 1), and cultured in ten 96-well plates (2×10⁵ cells per well). H5 HA binding was determined as described in Example 1. Culture supernatants from all wells on each plate (150 μl per well) were collected, and 50 μl per well were pooled and assayed for H5 HA binding. Week 1 analysis showed no reactivity, while reactivity was detected on Plates 6 and 9 on week 2. Culture supernatants from all wells on individual rows on Plates 6 and 9 were pooled and assayed for H5 HA binding as described in Example 1. Rows C and F on Plate 9 were reactive; however, the sample was lost due to fungal contamination after week 3, and screening was thus discontinued.

FIG. 16. Lack of H5 HA specific IgG in culture supernatants derived from immortalized B cells from TNSL B sample. EBV-immortalized B cells from TNSL B were stimulated to produce IgG with anti-human IgM (Fab′)₂, CD40L and BAFF (see Example 1), and cultured in ten 96-well plates (2×10⁵ cells per well). H5 HA binding was determined as described in Example 1. Culture supernatants from all wells on each plate (150 μl per well) were collected, and 50 μl per well were pooled and assayed for H5 HA binding. Week 1 analysis (4-11-07) showed low level reactivity on Plate 3, and culture supernatant from row D on this plate was weakly reactive on week 2; however, after weeks 3 and 4, no H5 HA-reactivity could be detected on any of the plates, and screening was thus discontinued.

FIG. 17. Lack of H5 HA specific IgG in culture supernatants derived from immortalized B cells from TNSL C sample. EBV-immortalized B cells from TNSL C were stimulated to produce IgG with anti-human IgM (Fab′)₂, CD40L and BAFF (see Example 1), and cultured in ten 96-well plates (>2×10⁵ cells per well). H5 HA binding was determined as described in Example 1. Culture supernatants from all wells on each plate (150 μl per well) were collected, and 50 μl per well were pooled and assayed for H5 HA binding. Week 1 analysis showed very low level reactivity on plates 7, 8, 9, and 10; however, after weeks 2 and 3, no H5 HA-reactivity could be detected on any of the plates, and screening was thus discontinued.

FIG. 18. Immortalized tonsil B cells produced very little or no H5 HA reactive IgG after one week of culture, from TNSL D sample. EBV-immortalized tonsil B cells from TNSL D were stimulated to produce IgG with anti-human IgM (Fab′)₂, CD40L and BAFF (see Example 1), and were cultured in ten 96-well plates at 1.5×10⁵ cells per well. One week later, culture supernatants from all wells on each plate (150 μl per well) were collected and 50 μl of each was pooled, and then tested for H5 HA binding as described in Example 1. Significant H5 HA specific binding was not detected on any plates. Mean absorbance levels at OD₄₀₅±SD of samples and controls (n=3) are shown.

FIG. 19. Immortalized tonsil B cells on Plate 10 produced IgG that specifically binds H5 HA after two weeks of culture, from TNSL D sample. EBV-immortalized tonsil B cells from TNSL D sample were cultured in ten 96-well plates at 1.5×10⁵ cells per well. 2 weeks later, 150 μl of culture supernatants from all wells on each plate were collected and 50 μl were pooled, then tested for H5 HA binding as described in Example 1. H5 HA specific binding was detected on Plates 1, 8, 9 and 10, with highest reactivity on Plate 10. Mean absorbance level at OD₄₀₅±SD of samples and controls (n=3) are shown.

FIG. 20. H5 HA specific IgG production identified in culture supernatant from paired adjacent wells on row G of Plate 10, from TNSL D sample. Culture supernatants from EBV immortalized B-cells from TNSL D sample (150 μl per well) were collected from each well after 3 weeks of culture, and 50 μl per sample from paired adjacent wells on reactive plates 1, 8, 9, and 10 were pooled and assayed for H5 HA binding as described in Example 1. Row G, wells 3 and 4 (green) had the highest H5 HA binding, similar to human serum controls. Mean absorbance levels at OD₄₀₅±SD of samples and controls (n=3) are shown.

FIG. 21. Identification of H5 HA reactive IgG in well G4 on Plate 10, from TNSL D sample. Culture supernatants from EBV immortalized B-cells from TNSL D sample (50 μl per well) on plate 10, Row G, wells 3 and 4 were tested for H5 HA binding as described in Example 1. Row G, well 4 (green) had the highest H5 HA binding, and cells from this well were selected for continued sub-cloning. Mean absorbance levels at OD₄₀₅±SD of samples and controls (n=3) are shown.

FIG. 22. Subcloning strategy for isolating H5 HA specific B cell clones from TNSL D sample. EBV-immortalized tonsil B cells from TNSL D sample were stimulated to produce IgG with anti-human IgM (Fab′)₂, CD40L and BAFF (see Example 1), and were cultured in ten 96-well plates at 1.5×10⁵ cells per well. One week later, culture supernatants from all wells on each plate (150 μl per well) were collected and 50 μl of each was pooled, and then tested for H5 HA binding as described in Example 1. After one week, no plates had H5 HA reactive IgG. However, after two weeks plates 1, 8, 9 and 10 were reactive, with Plate 10 exhibiting strong reactivity. Culture supernatants from individual rows on plates 1, 8 and 9 were analyzed on week 3; and supernatant from adjacent paired wells for each row on plate 10 were pooled and assayed simultaneously. Paired wells 3 and 4 in Row G on Plate 10 produced H5 HA reactive IgG, and production was subsequently localized to well G4, which was subcloned by limiting dilution analysis into 96-well plates containing 1, 10, 100, or 1000 cells per well. H5 HA reactive IgG was identified at weeks 7 and 8 in plates containing 100 and 1000 cells per well. Isolation of a single cell clonal population is currently ongoing. H5 HA reactivity could no longer be identified from plates 1, 8 and 9 after three weeks, at which point screening was discontinued.

FIG. 23. Immortalized tonsil B cells produced very little or no H5 HA reactive IgG after one week of culture, from TNSL E sample. EBV-immortalized tonsil B cells from TNSL E sample were stimulated to produce IgG with anti-human IgM (Fab′)₂, CD40L and BAFF (see Example 1), and were cultured in four 96-well plates at 10⁵ cells per well. One week later, culture supernatants from all wells on each plate (150 μl per well) were collected and 50 μl of each was pooled, and then tested for H5 HA binding as described in Example 1. Significant H5 HA specific binding was not detected on any plate above negative control purified human IgG. Mean absorbance level at OD₄₀₅±SD of samples and controls (n=3) are shown.

FIG. 24. H5 HA reactive IgG was detected in culture supernatants from individual rows on Plates 1 and 3, from TNSL-E sample. EBV-immortalized tonsil B cells from TNSL E sample were stimulated to produce IgG with anti-human IgM(Fab′)₂, CD40L and BAFF (see Example 1), and were cultured in four 96-well plates at 10⁵ cells per well. Two weeks later, culture supernatants from all wells on each plate (150 μl per well) were collected and 50 μl of each was pooled from individual rows on plates 1 and 3, and then tested for H5 HA binding as described in Example 1; supernatants from all wells on plates 2 and 4 were pooled and simultaneously assayed. Row A of plate 3 and rows E and B of plate 1 had significant levels of H5 HA reactive IgG, and were subjected to further analysis. Mean absorbance level at OD₄₀₅±SD of samples and controls (n=3) are shown.

FIG. 25. H5 HA specific IgG production identified in culture supernatant from pooled adjacent wells on Plates 3, 5, and 6, from TNSL E sample. Week 3 TNSL-E culture supernatants from pairs of adjacent wells in plate 1, rows B and E, and plate 3, row A were pooled and assayed for H5 HA binding activity as described in Example 1. Plate 1 row B, wells 5 and 6; Plate 1 row E, wells 11 and 12, 3 and 4; and Plate 3, row A, wells 9 and 10 exhibited H5 HA reactive IgG production and were selected for individual analysis. Mean absorbance level at OD₄₀₅±SD of samples and controls (n=3) are shown.

FIG. 26. Identification of H5 HA reactive IgG production in culture supernatant from individual wells on reactive plates, from TNSL E sample. Week 4 culture supernatants from individual wells B5 and B6, E3 and E4, E11 and E12 on Plate 1, and wells A9 and A10 on Plate 3, were assayed for H5 HA binding as described in Example 1. Strong H5 HA binding was observed from well A10 on plate 3, which and was selected for subcloning. Mean absorbance level at OD₄₀₅±SD of samples and controls (n=3) are shown.

FIG. 27. H5 HA specific IgG production was identified in culture supernatant two weeks after subcloning on plates containing 1000 cells per well, from TNSL E sample. Two weeks after subcloning immortalized B cells by limiting dilution analysis, culture supernatants from each of the plates were pooled and assayed for H5 HA binding as described in Example 1. H5 HA binding was only observed in supernatants from the 1000 cells/well plate. Further subcloning analysis is ongoing. Mean absorbance level at OD₄₀₅±SD of samples and controls (n=3) are shown.

FIG. 28. Subcloning strategy for isolating H5 HA reactive B cells from TNSL E sample. EBV-immortalized tonsil B cells from TNSL E sample were stimulated to produce IgG with anti-human IgM(Fab′)₂, CD40L and BAFF (see Example 1), and were cultured in four 96-well plates at 10⁵ cells per well. Culture supernatants from all wells on each plate (150 μl per well) were collected after one week, and 50 μl from each well was pooled and assayed by ELISA as described in Example 1, but significant binding was not detected above controls. After two weeks, 150 μl of supernatant was collected from all wells, then 50 μl from each well was pooled from individual rows on plates 1 and 3, and from all wells on plates 2 and 4, and were simultaneously assayed for H5 HA binding. Plate 1 rows B and E and Plate 3 row A were reactive after two weeks. The following week, supernatants from paired adjacent wells in the reactive rows were pooled and analyzed for H5 HA reactivity. B cells from reactive well A10 on Plate 3 were subsequently subcloned by limiting dilution analysis into 96-well plates containing 1, 10, 100, or 1000 cells per well. Starting one week later, the culture supernatants from each well were collected weekly and pooled from these plates; reactivity was seen in the 1000 cell per well plate, and isolation of H5 HA reactive IgG producing single cell clones is ongoing.

FIG. 29 Identification of H5 HA reactive IgG in pooled wells from TNSL-E subclones but loss of activity in TNSL-D, PBMC-A1 and A2 subclones. H5 HA reactive IgG was previously identified in TNSL D repertoire on plate 10 well G4, and in TNSL E repertoire on plate 3 well A10 (shaded insets). The cells in these wells were subcloned into 96-well plates at 1000, 100, or 1 cell per well. 3 weeks after subcloning, culture supernatants from each plate were pooled and assayed for H5 HA binding by ELISA as described in Example 1. Culture supernatant from clones previously isolated from PBMC-A1 and A2 repertoires were simultaneously tested. Controls consisted of human serum from volunteer (V5), previously found to be H5 HA reactive (diluted 1:1000), and nonreactive purified human IgG (500 ng, Sigma). Mean absorbance±SD of samples and controls (n=3) are shown.

FIGS. 30A-C Isolation of H5 HA reactive clones from TNSL E repertoire. (FIG. 30A) Pooled culture supernatants from individual rows on plate containing TNSL-E subclones (FIG. 29, 1000 cells/well), were assayed for H5 HA binding by ELISA as described in Example 1. Strong H5 HA binding was observed in rows C and E. (FIG. 30B) Culture supernatants from individual wells in rows C and E were next assayed for H5 HA binding by ELISA. Cells in reactive wells C7 and E3 were then subcloned by 2 additional rounds of limiting dilution cloning. (FIG. 30) Culture supernatants from resulting clones C7F6 and E3A5 were tested for H5 HA binding by ELISA. In all cases, controls consisted of reactive human serum from volunteer V5 (1:1000 dilution), and purified human IgG (500 ng, Sigma). Mean absorbance±SD of samples and controls (n=3) are shown.

FIG. 31 TNSL-E clones E3A5 and C7F6 secrete IgG that binds H5 HA with higher affinity than H1 or H7 HA, while human sera from healthy volunteers bind H1 HA with higher affinity. Sera from 5 healthy adult volunteers (diluted 1:1000), and culture supernatants from TNSL-E clones E3A5 and C7F6, were assayed for IgG binding to H1, H5 and H7 HA by ELISA, as described in Example 1. H1 strain is currently responsible for most human influenza virus infections and is targeted by flu vaccines, while H5 and H7 are avian influenza virus strains. Mean absorbance±SD of samples and controls (n=3) are shown.

FIGS. 32A-B Tonsil Sample E isolates E3A5 and C7F6 secrete significant amounts of IgG. E3A5 and C7F6 cells were washed once with DPBS, and seeded at the indicated numbers in 0.2 ml of media into wells of a 96-well plate. Supernatants (0.1 ml) were collected 72 hr later and (A) assayed for human IgG and IgM levels, as described in Example 1. Both isolates secreted IgG in a cell number dependent pattern, with no significant amounts of IgM being produced. Mean values±SD of samples (n=3) are shown. (B) The table shows production of IgG for each isolate, calculated as picograms of IgG secreted by 1 cell over the period of 24 hours. Each value represents means±SD of 12 samples.

FIG. 33 Tonsil Sample E isolates E3A5 and C7F6 secrete IgGI. E3A5 and C7F6 cells were washed once with DPBS, and seeded into T25 flasks at 10⁶ cells/flask and 10 ml culture media. Supernatants (5 ml) were collected 96 hr later and assayed for the presence of human IgG isotypes, using mouse-derived monoclonal antibodies against human IgG1, IgG2 and IgG3, as described in Example 1. The standard goat anti-human IgG-AP was used as a positive control. Both isolates secreted IgG1, with no detectable amounts of IgG2 or IgG3 being produced. Mean values±SD of samples (n=3) are shown.

FIGS. 34A-B Identification of light and heavy chain variable regions comprising the H5 HA reactive IgG1 molecules produced by TE-3A10-E3A5 and -C7F6 clones. Sequences of forward (black) and reverse (red) primers used to amplify light (X, ic) and heavy chain (V_(H)) immunoglobulin genes are listed in table (FIG. 34A). Primers were optimized to amplify the maximum number of potential variable region sequences (adapted from Welschof et al, 1995, J. Immunol. Methods, 179: 203-214). Restriction enzyme cleavage site sequence for XbaI (blue) was added to the forward primers, and Sail (red) was added to reverse primers for subsequent cloning and sequencing of the amplification products (SEQ ID NOS:1-15). (FIG. 34B) PCR amplification of cDNA from E3A5 and C7F6 H5 HA reactive clones was performed using each primer pair, and all PCR products were sequenced (see appendix). Both clones expressed X1 light chain variant; E3A5 expressed V_(H3) heavy chain gene, and C7F6 expressed V_(H1), indicating that the two clones had unique origins, and were not derived from a common precursor. (*Minor PCR bands resulted from 3′ primer homology between 21-xba with 2 3-xba and 2 4a-xba primers as confirmed by sequencing.) Lane M: marker=1 kb Plus ladder from Gibco-BRL; arrow indicates location of 500 bp band.

FIGS. 35A-E DNA and amino acid sequences of the heavy and light chain variable regions of the H5 HA reactive clones, TE-3A10-E3A5 and -C7F6. PCR products described in FIG. 34 were sequenced and analyzed. Results of the analysis are shown for light chains (FIGS. 35A and B) (SEQ ID NOS:16, 17, 18, 19, 20 and 21) and heavy chains (SEQ ID NOS:22, 23, 24, 25, 26, and 27) (FIGS. 35C and D) of E3A5 and C7F6, respectively. The DNA sequences of the clones are aligned against the germ-line sequences, which have the closest homology. Any changes in the DNA code are depicted below, and changes in the amino acid sequence are highlighted in yellow above. Sequences of different segments and the junction region are color-coded, as follows: variable (V) segments, diversity (D) segments, joining (J) segments, P nucleotides, N nucleotides. Comparison of the complementarity determining regions of both clones is shown in (FIG. 35E). *Mutations in the D-J region of C7F6 heavy chain made exact prediction of the CDR3 terminal location unreliable by VBASE2 software (SEQ ID NOS:28, 29, 30 and 31).

FIG. 36. Determination of optimal ELISA conditions for PLGF binding: binding buffers. Purified PLGF was brought to 4 μg/ml in the indicated binding buffers and bound to ELISA plates overnight at 4° C. 100 μl of 100 ng/ml PLGF mAb(mouse IgG1) was added to each well and incubated for 1 hr at RT. PLGF and PLGF mAbconcentrations were determined in previous optimization experiments. Isotypecontrol: purified mouse IgGat 1000 ng/ml; human serum from healthy volunteer (V-2) diluted 1:1000; purified human IgG(Sigma) at 5000 ng/ml. Isotypecontrol and PLGF mAbbinding were detected with goat anti-mouse IgG-AP; human serum and purified human IgGbinding were detected with goat anti-human IgG-AP (both secondaries diluted 1:10,000). Neutral Dulbecco's phosphate buffered saline solution (D-PBS) was chosen. Similar assays were developed for SEB, SEC2, ricin subunit B, and IL6.

FIGS. 37A-C Rapid screening strategy for SE Bre activity in tonsil X repertoire. Tonsil repertoire TNSL-X was immortalized as summarized in Table 7 and cultured in 10 96-well plates. (FIG. 37A) Two weeks later, culture supernatants from corresponding wells on all of the 10 plates, e.g., all A1 wells, were pooled and tested for SEB binding, on a single 96-well ELISA plate. Wells A8 and H3 (highlighted) were significantly increased above background, indicating that wells A8 and H3 each were positive on one of the 10 plates. (FIG. 37B) Simultaneously, aliquots of the same culture supernatants from all wells on each plate were pooled and assayed for SEB binding by ELISA, which indicated that plates 4 and 8 had reactivity. OD₄₀₅ absorbance values for each well minus the plate average are shown. (FIG. 37C) Combining the wells A8 and H3 reactivity in (FIG. 37A) with plates 4 and 8 reactivity in (FIG. 37B), the inventors confirmed that plate 8 well A8 and plate 4 well H3 (TX4A8 and TX8H3) were SEB reactive by testing their culture supernatants. Controls consisted of mouse anti-SEB monoclonal antibody diluted 1:5000 (greenbar).

FIGS. 38A-B Confirmation of repertoire SEB reactivity and screening of primary subclone plate pools. (FIG. 38A) Tonsil repertoires TR, TS, TV, and TX were screened for SEB reactivity as in FIG. 2. Wells with confirmed reactivity were chosen for primary subcloning. (FIG. 38B) All wells on each primary subclone plate were pooled and screened for SEB reactivity. TR and TS subclones lost reactivity, while Reactivity was detected at varying levels on TV and TX pooled subclones on each plate.

FIG. 39 Screening of TV-6F7 primary subclone plates for SEB reactivity. Plates were screened by ELISA ˜2 weeks after primary subcloning. TV-6F7-2H6, -3E2 and -3E4 were chosen for secondary subcloning at 50 cells per well, 3 plates each.

FIG. 40 Screening of TX-4H3 primary subclone plates for SEB reactivity. Plates were screened by ELISA ˜2 weeks after primary subcloning. TX-4H3-1E7, 3C6 and 3D8 were chosen for secondary subcloning at 50 cells per well, 3 plates each.

FIG. 41 Screening of TX-8A8 primary subclone plates for SEB reactivity. Plates were screened by ELISA ˜2 weeks after primary subcloning. TX-8A8-1C6, 3D7 and 3F4 were chosen for secondary subcloning at 50 cells per well, 3 plates each.

FIGS. 42A-B Confirmation of repertoire SEC2 reactivity and screening of primary subclone plate pools. (FIG. 42A) Tonsil repertoires TR and TS were screened for SEC2 reactivity using the strategy from FIG. 2. Wells with confirmed reactivity (TR-10A4, -10E12, TS-6C5) were chosen for primary subcloning. (FIG. 42B) All wells on each primary subclone plate were pooled and screened for SEC2 reactivity. Tonsil repertoire TV was also screened, resulting in identification of well TV-bB2 with SEC2 reactivity. TR and TS subclones lost reactivity. Well TV-bB2 was selected for primary subcloning, 3 plates.

FIGS. 43A-B Screening of TX-bB2 primary subclone plates for SEC2 reactivity. Plates were screened by ELISA ˜2 weeks after primary subcloning. (FIG. 43A) All wells on each primary subclone plate were pooled and screened for SEC2 reactivity, which was detected on plate 2. (FIG. 43B) TV-bB2-2E1 and 2F2 were chosen for secondary subcloning at 50 cells per well, 2 plates each.

FIGS. 44A-B Screening of tonsil repertoire TW and confirmation of PLGF reactivity. (FIG. 44A) Culture supernatants from corresponding wells on all of the 10 plates, e.g., all A1 wells, were pooled and tested for PLGF binding, on a single 96-well ELISA plate. Well E12 (highlighted) was significantly increased above background, indicating that well E12 was positive on one of the 10 plates. (FIG. 44B) Culture supernatants from E12 wells on each of the 10 TW repertoire plates were individually screened for PLGF reactivity by ELISA. Plate 1 well E12 had significant reactivity, and was chosen for subcloning, 5 plates, 1000 cells/well.

FIGS. 45A-B Screening of TW-1E12 primary subclone plates for PLGF reactivity. Plates were screened by ELISA ˜2 weeks after primary subcloning. (FIG. 45A) All wells on each primary subclone plate were pooled and screened for SEC2 reactivity, which was detected on plates 2 and 5. (FIG. 45B) Individual wells on plates 2 and 5 were screened for PLGF reactivity. TW-2E3, 2G9, 5A10 were chosen for secondary subcloning at 50 cells per well, 3 plates each.

FIGS. 46A-C Screening of tonsil repertoire TZ and confirmation of PLGF reactivity. (FIG. 46A) Culture supernatants from corresponding wells on all of the 10 plates, e.g., all A1 wells, were pooled and tested for PLGF binding, on a single 96-well ELISA plate. Wells B10, F9 (highlighted) were significantly increased above background, indicating that wells B10, F9 were positive on one of the 10 plates. (FIG. 46B) Pooled supernatants from all wells on each of the 10 TZ repertoire plates were screened, indicating that plates 3 and 5 had PLGF reactivity. (FIG. 46C) Combining reactivity in wells B10 and F9 with plates 3 and 5, this confirmed that TZ-3B10 and TZ-5F9 had significant reactivity, and were thus chosen for primary subcloning, 3 plates each, 1000 cells/well.

FIGS. 47A-C Screening of tonsil repertoire TZ and confirmation of ricin B reactivity. (FIG. 47A) Culture supernatants from 6F10 corresponding wells on all of the 10 plates, e.g., all A1 wells, were pooled and tested for ricin B binding, on a single 96-well ELISA plate. Wells B8, F10 (highlighted) were significantly increased above background, indicating that wells B8, F10 were positive on one of the 10 plates. (FIG. 47B) Pooled supernatants from all wells on each of the 10 TZ repertoire plates were screened, indicating that plates 6 and 7 had ricin B reactivity. (FIG. 47C) Combining reactivity in wells B8 and F10 with plates 6 and 7 confirmed that TZ-6F10 and TZ-7B8 had significant reactivity, and were thus chosen for primary subcloning, 5 plates each, 100 cells/well.

FIG. 48 Screening of TZ-7B8 primary subclone plates for ricin B reactivity. Plates were screened by ELISA ˜3 weeks after primary subcloning. TZ-7B8 1A12, 1 E3, 2A1, 2A3, 4A1 were chosen for secondary subcloning.

FIG. 49 Screening of TZ-6F10 primary subclone plates for ricin B reactivity. Plates were screened by ELISA ˜3 weeks after primary subcloning. TZ-6F10 1C3, 1D6, 1F11, 2F2, 2G2, 3E1, 4H4, 4G6, 5D7 were chosen for secondary subcloning.

FIGS. 50A-C Rapid screening strategy for H5 HA reactivity in tonsil N repertoire. Tonsil repertoire N (TNSL-N) was immortalized with Epstein-Barr virus, induced to differentiate with recombinant human Baff, soluble CD40L and anti-human IgM (Fab′)₂, and cultured in ten 96-well plates (Feb. 5, 2008) as summarized in Table 16. (FIG. 50A) Three weeks later, culture supernatants from corresponding wells on all of the 10 plates, e.g. all A1 wells, were pooled and tested for H5 HA binding on a single 96-well ELISA plate. Well G7 (highlighted) was significantly increased above background, indicating that well G7 was positive on one of the 10 plates. (FIG. 50B) Simultaneously, aliquots of the same culture supernatants from all wells on each plate were pooled and assayed for H5 HA binding by ELISA on Mar. 3, 2008, which indicated that plate 6 had reactivity (blue bar). OD405 absorbance values for each well minus the antigen free background are shown. (FIG. 50C) Combining the well G7 reactivity shown in (FIG. 50A) with plate 6 reactivity shown in (FIG. 50B), it was confirmed that plate 6 well G7 (TN 6G7) was H5 HA reactive by testing the culture supernatant by ELISA on Mar. 4, 2008, (blue bar). Controls consisted of H5 HA-reactive clone E3A5 supernatant, H5 HA-reactive human serum (diluted 1:500) and non-reactive human IgG (diluted 1:300; green bars).

FIGS. 51A-C Screening of TN-6G7 primary subclones for H5 HA reactivity and selection of wells for secondary subcloning. (FIG. MA) Cells from well TN-6G7 were subcloned into ten 96-well plates (500 cells/well; primary subcloning). Two weeks later, culture supernatants from corresponding wells on all of the 10 plates were pooled and tested for H5 HA binding on a single 96-well ELISA plate. Several wells showed reactivity (highlighted in pale yellow) with wells C8 and F8 (highlighted and boxed) having significant reactivity above background, indicating that wells C8 and F8 were positive on at least one of the 10 plates. (FIG. 51B) Simultaneously, aliquots of these same culture supernatants were pooled from all wells on each plate and assayed for H5 HA binding by ELISA on Mar. 19, 2008, which indicated that plates 2, 3, 5, 7, and 8 (blue bars) had reactivity. OD₄₀₅ absorbance values for each well minus background (wells containing no antigen) are shown. (FIG. 51C) Combining the wells C8 and F8 reactivity in (FIG. 51A) with plates 2, 3, 5, 7, and 8 reactivity in (FIG. 51B), it was found that plate 7 well F8 (TN-6G7-7F8) had the highest H5 HA reactivity by ELISA testing of culture supernatants (highlighted blue bar); cells from that well were selected for secondary subcloning. Controls consisted of H5 HA-reactive clone E3A5 supernatant, H5 HA-reactive human serum (diluted 1:500) and non-reactive human IgG (diluted 1:300; green bars).

FIGS. 52A-B Screening of TN-6G7-7F8 secondary subclones for H5 HA reactivity and selection of wells for tertiary subcloning. (FIG. 52A) Cells from well TN-6G7-7F8 were subcloned into two 96-well plates (500 cells/well; secondary subcloning). Three weeks later, culture supernatants from corresponding wells on both plates were pooled and tested for H5 HA binding on a single 96-well ELISA plate. Several wells showed reactivity (highlighted in yellow) with well G7 showing the highest reactivity. (FIG. 52B) The wells with highest reactivity were identified by testing the culture supernatant on both plates from individual wells that gave positive results in (FIG. 52A). Plate 2 well G7 (TN-6G7-7F8-2G7) had the highest H5 HA reactivity by ELISA testing. Controls consisted of H5 HA-reactive clone E3A5 supernatant, and H5 HA-reactive human serum (diluted 1:500; green bars).

FIGS. 53A-B Initial characterization of clone TN-6G7-7F8-2G7. (FIG. 53A) Cells in well TN-6G7-7F8-2G7 were subcloned into 2 plates (50 cells/well); however, 4 weeks later, both plates had fungal contamination and were discarded. Following this, a frozen aliquot of TN 6G7-7F8-2G7 cells was thawed, briefly cultured and plated into two 96-well plates (50 cells/well, 60 wells/plate, tertiary subcloning). 4 weeks later, culture supernatants from both plates were tested for H5 HA binding on two 96-well ELISA plates. All wells demonstrated H5 HA reactivity, indicative of clonality. (FIG. 53B) IgG in the TN-6G7-7F8-2G7 supernatant was tested by a capture ELISA for IgG₁₋₄ subtypes. The results indicated that TN-6G7-7F8-2G7 cells secrete IgG₁. Purified human IgG (2 μg/ml, Sigma) was used as a positive control for detection of each IgG subtype.

FIGS. 54A-B Identification of light and heavy chain variable regions comprising the TN-6G7-7F8-2G7 H5 HA reactive IgG₁ molecule. TN-6G7-7F8-2G7 cells were collected and 2.5×10⁶ cells were incubated with H5 HA conjugated magnetic beads (bound through a HIS-tag on the H5 HA to anti-HIS mAb on the beads, THE™ MagBeads). Cells bound to the magnetic beads were lysed for RNA extraction. Sequences of forward (in black) and reverse (in red) primers used to amplify light (λ, κ) and heavy chain (VH) immunoglobulin genes are listed in table (FIG. 54A) (SEQ ID NOS:1-15). Primers were optimized to amplify the maximum number of potential variable region sequences (adapted from Welschof et al, 1995, J. Immunol. Methods, 179: 203-214). Restriction enzyme cleavage site sequence for XbaI (in blue) was added to the forward primers, and SalI (in red) was added to reverse primers for subsequent cloning and sequencing of the amplification products. (FIG. 54B) PCR amplification of cDNA obtained from 27,000 TN-6G7-7F8-2G7 cells recovered from magnetic beads conjugated to H5 HA (described in FIG. 53), indicated that TN-6G7-7F8-2G7 cells express λ1 light chain and VH3 heavy chain. (*Minor PCR bands resulted from 3′ primer homology between λ1-xba with λ3-xba and λ4a-xba primers). Lane M: marker=1 kb Plus ladder from Gibco-BRL; arrow indicates location of 500 bp band.

FIGS. 55A-C DNA and amino acid sequences of the heavy and light chain variable regions of the H5 HA reactive clone, TN-6G7. PCR products obtained as described in FIG. 54 were sequenced, and results of the analysis are shown for light chain (FIG. 55A) (SEQ ID NOS: 32, 33, 34 and 35) and heavy chain (SEQ ID NOS:36, 37, and 38) (FIG. 55B). The DNA sequences of the clones were aligned against the germ-line sequences, which have the closest homology. Amino acid numbering and CDR positioning were performed according to Kabat et al. (1991) as described in Sequences of Proteins of Immunological Interest. Any changes in the DNA code are depicted below, and changes in the amino acid sequence are highlighted in yellow above. Sequences of different segments and the junction region are color-coded, as follows: variable (V) segments, diversity (D) segments (in green), joining (J) segments (in blue), P nucleotides (in pink), N nucleotides (in red). Triple dots ( . . . ) indicate gaps in DNA and amino acid sequences that correspond to sequences present in some germline genes (but not in TN-6G7-7F8-2G7). Gaps were inserted to maintain amino acid alignments with Kabat convention. Dashes (-) indicate germline DNA sequences that are identical to the TN-6G7 sequence. (FIG. 55C) Complementarity determining regions of TN-6G7 light chain and heavy chain genes are depicted. Single dots (.) indicate gaps that have been inserted for CDR alignment purposes (see above).

FIG. 56 Determination of dissociation constants (Kd) for E3A5 human mAbs. Competitive ELISA methods were used to calculate Kd. First, transfer experiments were used to determine conditions under which less than 10% of total antibody bound to the ligand coating the wells. Titration of a constant antibody concentration equilibrated with different concentrations of his-H5 HA was used to calculate Kd for E3A5. υ, bound antibody fraction; [Ag], concentration of free antigen.

FIGS. 57A-B Generation of recombinant expression vectors for large scale production of E3A5 and C7F6 human mAbs. (FIG. 57A) full length light and heavy IgG1 chains for both E3A5 and C7F6 have been generated by PCR using primers to leader and C-terminal sequences. (FIG. 57B) Construction of retrovirus vectors expressing E3A5 and C7F6 light chains in combination with NeoR selection marker, and heavy chains in combination with EGFP fluorescent marker.

FIGS. 58A-B ELISA analysis and human immunoglobulin (Ig) variable region identification in Ricin B subcloned cells TZ-6F10⁻⁴H4 and TZ-7B8-2A3. (FIG. 58A) TZ-6F10 and TZ-7B8 subclones were tested by ELISA for ricin subunit B binding 2 weeks after secondary subcloning at 25-500 cells per well (# cells per well listed at top of graph). TZ-6F10⁻⁴H4 and T7-7B8-2A3 subclones were chosen for Ig gene analysis since both had significant activity, arising from 25 or 50 cells per well. (FIG. 58B) RT-PCR was performed on cells in wells TZ-6F10⁻⁴H4 and TZ-7B8-2A3 using primer sequences listed in FIGS. 34A and 54A, using same PCR conditions. Each well contained 11/3 and 16 sequences, and VH1 and VH3 sequences. All amplified sequences were subsequently sequenced.

FIGS. 59A-F DNA and amino acid sequences of the heavy and light chain variable regions of ricin B reactive subcloned cells TZ-6F10⁻⁴H4 and TZ-7B8-2A3. PCR products were sequenced and analyzed as described in Methods. Results of the analyses are shown for light chains: TZ-6F10 (FIG. 59A) (SEQ ID NOS:47, 48, 49 and 50) TZ-7F8 (FIGS. 59C, D) (SEQ ID NOS:55, 56, 57, 58, 59, 60, 61 and 62) and heavy chains TZ-6F10 (FIG. 59B) (SEQ ID NOS:51, 52, 53 and 54), TZ-7B8 (FIG. 59E) (SEQ ID NOS:63, 64, 65 and 66). The DNA sequences of the clones were aligned against the germ-line sequences, which have the closest homology. Amino acid numbering and CDR positioning were done according to Kabat et al. (1991) as described in Sequences of Proteins of Immunological Interest. Any changes in the DNA code are depicted below, and changes in the amino acid sequence are highlighted in yellow above. Sequences of different segments and the junction region are color-coded, as follows: variable (V) segments, diversity (D) segments, joining (J) segments, P nucleotides, N nucleotides. Triple dots ( . . . ) indicate gaps in DNA and amino acid sequences that correspond to sequences present in some (but not in our) germline genes. Gaps are inserted to maintain amino acid alignments with Kabat convention. Dashes (-) indicate germline DNA sequences that are identical to our sequences. (FIG. 59F) (SEQ ID NOS:67, 68, 69, 70 and 71) Complementarity determining regions of each of the sequences. Dots (.) indicate gaps that have been inserted for CDR alignment purposes (see above).

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

A variety of prior efforts have been directed at the production of human monoclonal antibodies, including EP 0 218 158, EP 0 161 941, U.S. Pat. No. 5,024,946, U.S. Patent Publication No. 2006/0252124, Traggia et al. (2004) and Lanzavecchia et al. (2006). However, to date there remains a need for improved methods of human antibody selection.

The present invention provides a solution to various problems limiting the prior work on human monoclonals. In particular, by targeting B-cells that have not undergone immunoglobulin isotype class switching, i.e., are still IgM+, and transforming these cells with a high efficiency EBV transformation protocol, the inventors have been able to select rare B-cells that secrete human monoclonal antibodies. In addition, they have optimized a cocktail of cytokines/growth factors/signaling agents that efficiently induce immunoglobulin isotype class switching from IgM to IgG in the EBV-immortalized B-cells.

I. TARGET ANTIGENS

Virtually any antigen may be utilized to select a B-cell in accordance with the present invention. These include toxins, cellular receptors (e.g., for virus entry, bacterial entry, fungus entry, parasite entry, toxin entry), tumor antigens, cytokine/chemokine/growth factors, cytokine/chemokine/growth factor receptors, an inflammation mediator, pain mediator, tissue injury/damage mediator, an antigen on activation molecules/ligands/receptors, an antigen on costimulatory molecules/ligands/receptors, a molecule mediating innate immunity, a cellular adhesion molecule, a cellular adhesion receptor, an over-expressed/under-glycosylated/oxidized/misfolded/mutated cellular proteins (“altered self” antigens), a molecule/ligand/receptor mediating cell apoptosis, or a growth inhibitory molecule. This list is not exhaustive and is provided for exemplification only.

A. Infectious Agents

A variety of infectious agents have antigens that can serve as targets in the present invention. For example, bacteria, molds & fungi, parasites and viruses all present antigens that are suitable targets for antibodies.

1. Influenza

The influenza virus is an RNA virus of the family Orthomyxoviridae, which comprises the influenzaviruses, Isavirus and Thogotovirus. There are three types of influenza virus: Influenzavirus A, Influenzavirus B or Influenzavirus C. Influenza A and C infect multiple species, while influenza B almost exclusively infects humans. The type A viruses are the most virulent human pathogens among the three influenza types, and cause the most severe disease. The Influenza A virus can be subdivided into different serotypes based on the antibody response to these viruses. The serotypes that have been confirmed in humans, ordered by the number of known human pandemic deaths, are:

-   -   H1N1 caused “Spanish Flu”     -   H2N2 caused “Asian Flu”     -   H3N2 caused “Hong Kong Flu”     -   H5N1 is a pandemic threat in 2006-7 flu season     -   H7N7 has unusual zoonotic potential     -   H1N2 is endemic in humans and pigs     -   H9N2, H7N2, H7N3, H10N7

Influenza B virus is almost exclusively a human pathogen, and is less common than influenza A. The only other animal known to be susceptible to influenza B infection is the seal. This type of influenza mutates at a rate 2-3 times lower than type A and consequently is less genetically diverse, with only one influenza B serotype. As a result of this lack of antigenic diversity, a degree of immunity to influenza B is usually acquired at an early age. However, influenza B mutates enough that lasting immunity is not possible. This reduced rate of antigenic change, combined with its limited host range (inhibiting cross species antigenic shift), ensures that pandemics of influenza B do not occur. The influenza C virus infects humans and pigs, and can cause severe illness and local epidemics. However, influenza C is less common than the other types and usually seems to cause mild disease in children. The three strains with substantial enough pathology every year to be included as components of the trivalent vaccine are the influenza A strains H1N1 and H2N3, and influenza B.

The following applies for all influenza viruses, although other strains are very similar in structure: the influenza A virus particle or virion is 80-120 nm in diameter and usually roughly spherical, although filamentous forms can occur. Unusually for a virus, the influenza A genome is not a single piece of nucleic acid; instead, it contains eight pieces of segmented negative-sense RNA (13.5 kB total), which encode 11 proteins (HA, NA, NP, M1, M2, NS1, NEP, PA, PB1, PB1-F2, PB2). The best-characterised of these viral proteins are hemagglutinin and neuraminidase, two large glycoproteins found on the outside of the viral particles. Neuraminidase is an enzyme involved in the release of progeny virus from infected cells, by cleaving sugars that bind the mature viral particles. By contrast, hemagglutinin is a lectin that mediates binding of the virus to target cells and entry of the viral genome into the target cell. The hemagglutinin (HA or H) and neuraminidase (NA or N) proteins are targets for antiviral drugs. These proteins are also recognised by antibodies, i.e., they are antigens. The responses of antibodies to these proteins are used to classify the different serotypes of influenza A viruses, hence the Hand N in H5N1.

Influenza viruses bind through hemagglutinin onto sialic acid sugars on the surfaces of epithelial cells; typically in the nose, throat and lungs of mammals and intestines of birds. The cell imports the virus by endocytosis. In the acidic endosome, part of the haemagglutinin protein fuses the viral envelope with the vacuole's membrane, releasing the viral RNA (vRNA) molecules, accessory proteins and RNA-dependent RNA transcriptase into the cytoplasm. These proteins and vRNA form a complex that is transported into the cell nucleus, where the RNA-dependent RNA transcriptase begins transcribing complementary positive-sense vRNA. The vRNA is either exported into the cytoplasm and translated, or remains in the nucleus. Newly-synthesised viral proteins are either secreted through the Golgi apparatus onto the cell surface or transported back into the nucleus to bind vRNA and form new viral genome particles. Other viral proteins have multiple actions in the host cell, including degrading cellular mRNA and using the released nucleotides for vRNA synthesis and also inhibiting translation of host-cell mRNAs.

Negative-sense vRNAs that form the genomes of future viruses, RNA-dependent RNA transcriptase, and other viral proteins are assembled into a virion. Hemagglutinin and neuraminidase molecules cluster into a bulge in the cell membrane. The vRNA and viral core proteins leave the nucleus and enter this membrane protrusion. The mature virus buds off from the cell in a sphere of host phospholipid membrane, acquiring hemagglutinin and neuraminidase with this membrane coat. As before, the viruses adhere to the cell through hemagglutinin; the mature viruses detach once their neuraminidase has cleaved sialic acid residues from the host cell. After the release of new influenza virus, the host cell dies.

Because of the absence of RNA proofreading enzymes, the RNA-dependent RNA transcriptase makes a single nucleotide insertion error roughly every 10 thousand nucleotides, which is the approximate length of the influenza vRNA. Hence, nearly every newly-manufactured influenza virus is a mutant. The separation of the genome into eight separate segments of vRNA allows mixing or reassortment of vRNAs if more than one viral line has infected a single cell. The resulting rapid change in viral genetics produces antigenic shifts and allow the virus to infect new host species and quickly overcome protective immunity. This is important in the emergence of pandemics, as discussed in Epidemiology.

i. Vaccination

Vaccination against influenza with an active flu vaccine is strongly recommended for high-risk groups, such as children and the elderly. These vaccines can be produced in several ways; the most common method is to grow the virus in fertilised hen eggs. After purification, the virus is inactivated (for example, by treatment with detergent) to produce an inactivated-virus vaccine. Alternatively, the virus can be grown in eggs until it loses virulence and the avirulent virus given as a live vaccine. The effectiveness of these flu vaccines is variable. As discussed above, due to the high mutation rate of the virus, a particular flu vaccine usually confers protection for no more than a few years. Every year, the World Health Organization predicts which strains of the virus are most likely to be circulating in the next year, allowing pharmaceutical companies to develop vaccines that will provide the best immunity against these strains. Vaccines have also been developed to protect poultry from avian influenza. These vaccines can be effective against multiple strains and are used either as part of a preventative strategy, or combined with culling in attempts to eradicate outbreaks.

ii. Therapy

The two classes of anti-virals are neuraminidase inhibitors and M2 inhibitors (adamantane derivatives). Neuraminidase inhibitors are currently preferred for flu virus infections. The CDC recommended against using M2 inhibitors during the 2005-06 influenza season.

Antiviral drugs such as oseltamivir (trade name Tamiflu) and zanamivir (trade name Relenza) are neuraminidase inhibitors that are designed to halt the spread of the virus in the body. These drugs are often effective against both influenza A and B. The Cochrane Collaboration reviewed these drugs and concluded that they reduce symptoms and complications. Resistance has not yet been a problem with neuraminidase inhibitors. Resistant viruses have been identified but, unlike the situation with amantadine, in which the resistant viruses are fully virulent and able to transmit, that does not appear to be the case with neuraminidase. Different strains of influenza virus have differing degrees of resistance against these antivirals and it is impossible to predict what degree of resistance a future pandemic strain might have.

The antiviral drugs amantadine and rimantadine are designed to block a viral ion channel and prevent the virus from infecting cells. These drugs are sometimes effective against influenza A if given early in the infection, but are always ineffective against influenza B. In fact, measured resistance to amantadine and rimantadine in American isolates of H3N2 has increased to 91% in 2005. Monoclonal antibodies can inhibit neuraminaidase activity, M2, or hemagglutin binding to sialic acids. This one of the features of the technology described herein.

2. Other Viruses

In addition to influenza, a variety of other viruses may be used to generate antibodies, and subsequently be diagnosed or treated, by antibodies. Table 1 lists a variety of other virus targets for use with the present invention:

TABLE 1 VIRUSES Abelson murine leukemia virus, Retroviridae Adelaide River virus, Rhabdoviridae Adeno-associated virus 1, Parvoviridae Adeno-associated virus 2, Parvoviridae Adeno-associated virus 3, Parvoviridae Adeno-associated virus 4, Parvoviridae Adeno-associated virus 5, Parvoviridae African green monkey cytomegalovirus, Herpesviridae African green monkey HHV-like virus, Herpesviridae African green monkey polyomavirus, Papovaviridae African horse sickness viruses 1 to 10, Reoviridae African swine fever virus, African swine fever-like viruses Aleutian disease virus, Parvoviridae Aleutian mink disease virus, Parvoviridae American ground squirrel herpesvirus, Herpesviridae Baboon herpesvirus, Herpesviridae Baboon polyomavirus 2, Papovaviridae Bovine adeno-associated virus, Parvoviridae Bovine adenoviruses 1 to 9, Adenoviridae Bovine astrovirus 1, Astroviridae Bovine astrovirus 2, Astroviridae Bovine coronavirus, Coronaviridae Bovine diarrhea virus, Flaviviridae Bovine encephalitis herpesvirus, Herpesviridae Bovine enteric calicivirus, Caliciviridae Bovine enterovirus 1, Picornaviridae Bovine enterovirus 2, Picornaviridae Bovine ephemeral fever virus, Rhabdoviridae Bovine herpesvirus 1, Herpesviridae Bovine herpesvirus 2, Herpesviridae Bovine herpesvirus 4, Herpesviridae Bovine herpesvirus 5, Herpesviridae Bovine immunodeficiency virus, Retroviridae Bovine leukemia virus, Retroviridae Bovine mamillitis virus, Herpesviridae Bovine papillomavirus 1, Papovaviridae Bovine papillomavirus 2, Papovaviridae Bovine papillomavirus 4, Papovaviridae Bovine papular stomatitis virus, Poxviridae Bovine parainfluenza virus 3, Paramyxoviridae Bovine parvovirus, Parvoviridae Bovine polyomavirus, Papovaviridae Bovine respiratory syncytial virus, Paramyxoviridae Bovine rhinovirus 1, Picornaviridae Bovine rhinovirus 2, Picornaviridae Bovine rhinovirus 3, Picornaviridae Bovine syncytial virus, Retroviridae California encephalitis virus, Bunyaviridae California harbor sealpox virus, Poxviridae Canine adeno-associated virus, Parvoviridae Canine adenovirus 1, Adenoviridae Canine adenovirus 2, Adenoviridae Canine calicivirus, Caliciviridae Canine coronavirus, Coronaviridae Canine distemper virus, Paramyxoviridae Canine herpesvirus, Herpesviridae Canine minute virus, Paruoviridae Canine oral papillomavirus, Papovaviridae Canine parvovirus, Parvoviridae Chicken anemia virus, Circoviridae Chicken parvovirus, Paruoviridae Chimpanzee herpesvirus, Herpesviridae Cottontail herpesvirus, Herpesviridae Cottontail rabbit papillomavirus, Papovaviridae Cowpox virus, Poxviridae Deer fibroma virus, Papovaviridae Deer papillomavirus, Papovaviridae Elephant loxondontal herpesvirus, Herpesviridae Elephant papillomavirus, Papovaviridae Elephantid herpesvirus, Herpesviridae Epstein-Barr virus, Herpesviridae Equid herpesvirus 1, Herpesviridae Equid herpesvirus 2, Herpesviridae Equid herpesvirus 3, Nerpesviridae Equid herpesvirus 4, Herpesviridae Equid herpesvirus 5, Herpesviridae Equid herpesvirus 6, Herpesviridae Equid herpesvirus 7, Herpesviridae Equid herpesvirus 8, Herpesviridae Equine abortion herpesvirus, Herpesviridae Equine adeno-associated virus, Parvoviridae Equine adenovirus 1, Adenoviridae Equine arteritis virus, Arterivirus Equine cytomegalovirus, Herpesviridae Equine encephalosis viruses 1 to 7, Reoviridae Equine herpesvirus 1, Herpesviridae Equine herpesvirus 3, Herpesviridae Equine herpesvirus 4, Herpesviridae Equine herpesvirus 5, Herpesviridae Equine infectious anemia virus, Retroviridae Equine papillomavirus, Papovaviridae Equine rhinopneumonitis virus, Herpesviridae Equine rhinovirus 1, Picornaviridae Equine rhinovirus 2, Picornaviridae Equine rhinovirus 3, Picornaviridae European bat virus 1, Rhabdoviridae European bat virus 2, Rhabdoviridae European brown hare syndrome virus, Caliciviridae European elk papillomavirus, Papovaviridae European ground squirrel cytomegalovirus, Herpesviridae European hedgehog herpesvirus, Herpesviridae Feline calicivirus, Caliciviridae Feline herpesvirus 1, Herpesviridae Feline immunodeficiency virus, Retroviridae Feline infectious peritonitis virus, Coronaviridae Feline leukemia virus, Retroviridae Feline parlleukopenia virus, Parvoviridae Feline parvovirus, Parvoviridae Feline syncytial virus, Retroviridae Feline viral rhinotracheitis virus, Herpesviridae Field mouse herpesvirus, Herpesviridae Foot-and-mouth disease virus A, Picornaviridae Foot-and-mouth disease virus ASIA 1, Picornaviridae Foot-and-mouth disease virus C, Picornaviridae Foot-and-mouth disease virus O, Picornaviridae Foot-and-mouth disease virus SAT 1, Picornaviridae Foot-and-mouth disease virus SAT 2, Picornaviridae Foot-and-mouth disease virus SAT 3, Picornaviridae Goat herpesvirus, Herpesviridae Goatpox virus, Poxviridae Ground squirrel hepatitis B virus, Hepadnaviridae GroupA rotaviruses, Reoviridae Group B rotaviruses, Reoviridae Group C rotaviruses, Reoviridae Group D rotaviruses, Reoviridae Group E rotaviruses, Reoviridae Group F rotaviruses, Reoviridae Guinea pig cytomegalovirus, Herpesviridae Guinea pig herpesvirus 1, Herpesviridae Guinea pig herpesvirus 3, Herpesviridae Guinea pig t, vpe C oncovirus, Retroviridae Hamster herpesvirus, Herpesviridae Hamster polyomavirus, Papovaviridae Hantaan virus, Bunyaviridae Harbor seal herpesvirus, Herpesviridae Hare fibroma virus, Poxviridae Hepatitis A virus, Picornaviridae Hepatitis B virus, Hepadnaviridae Hepatitis C virus, Flaviviridae Herpesvirus M, Herpesviridae Herpesvirus papio, Herpesviridae Herpesvirus platyrrhinae type, Herpesviridae Herpesvirus pottos, Herpesviridae Herpesvirus saimiri 2, Herpesviridae Herpesvirus salmonis, Herpesviridae Herpesvirus sanguinus, Herpesviridae Herpesvirus scophthalmus, Herpesviridae Herpesvirus sylvilagus, Herpesviridae Herpesvirus T, Herpesviridae Herpesvirus tarnarinus, Herpesviridae Hog cholera virus, Flaviviridae Herpes simiae virus, Herpesviridae Herpes simplex virus 1, Herpesviridae Herpes simplex virus 2, Herpesviridae Herpes virus B, Herpesviridae Herpesvirus aotus 1, Herpesviridae Herpesvirus aotus 3, Herpesviridae Herpesvirus ateles strain 73, Herpesviridae Herpesvirus cuniculi, Herpesviridae Herpesvirus cyclopsis, Herpesviridae Human adenoviruses 1 to 47, Adenoviridae Human astrovirus 1, Astroviridae Human astrovirus 2, Astroviridae Human astrovirus 3, Astroviridae Human astrovirus 4, Astroviridae Human astrovirus 5, Astroviridae Human calicivirus, Caliciviridae Human caliciviruses, Caliciviridae Human coronavirus 229E, Coronaviridae Human coronavirus OC43, Coronaviridae Human coxsackievirusA 1 to 22, Picornaviridae Human coxsackievirus A 24, Picornaviridae Human coxsackievirus B 1 to 6, Picornaviridae Human cytomegalovirus, Herpesviridae Human echovirus 1 to 7, Picornaviridae Human echovirus 11 to 27, Picornaviridae Human echovirus 29 to 33, Picornaviridae Human echovirus 9, Picornaviridae Human enterovirus 68 to 71, Picornaviridae Human foamy virus, Retroviridae Human herpesvirus 1, Herpesviridae Human herpesvirus 2, Herpesviridae Human herpesvirus 3, Herpesviridae Human herpesvirus 4, Nerpesviridae Human herpesvirus 5, Herpesviridae Human herpesvirus 6, Herpesviridae Human herpesvirus 7, Herpesviridae Human immunodeficiency virus 1, Retroviridae Human immunodeficiency virus 2, Retroviridae Human papillomavirus 11, Papovaviridae Human papillomavirus 16, Papovaviridae Humanpapillomavirus 18, Papovaviridae Human papillomavirus 31, Papovaviridae Human papillomavirus 33, Papovaviridae Human papillomavirus 5, Papovaviridae Human papillomavirus 6b, Papovaviridae Human papillomavirus 8, Papovaviridae Human papillomavirus 1a, Papovaviridae Human parainfluenza virus 1, Paramyxoviridae Human parainfluenza virus 2, Paramyxoviridae Human parainfluenza virus 3, Paramyxoviridae Human parainfluenza virus 4a, Paramyxoviridae Human parainfluenza virus 4b, Paramyxoviridae Human poliovirus 1, Picornaviridae Human poliovirus 2, Picornaviridae Human poliovirus 3, Picornaviridae Human respiratory syncytial virus, Paramyxoviridae Human rhinovirus 1 to 100, Picornaviridae Human rhinovirus 1A, Picornaviridae Human spumavirus, Retroviridae Human T-lymphotropic virus 1, Retroviridae Human T-lymphotropic virus 2, Retroviridae Jaagsiekte virus, Retroviridae Japanese encephalitis virus, Flaviviridae JC virus, Papovaviridae Kirsten murine sarcoma yirus, Retroviridae Lagos bat virus, Rhabdoviridae Lymphocytic choriomeningitis virus, Arenaviridae Mice minute virus, Parvoviridae Mice pneumotropic virus, Papovaviridae Moloney murine sarcoma virus, Retroviridae Moloney virus, Retroviridae Monkeypox virus, Poxviridae Mouse cytomegalovirus 1, Herpesviridae Mouse Elberfield virus, Picornaviridae Mouse herpesvirus strain 68, Herpesviridae Mouse mammary tumor virus, Retroviridae Mouse thymic herpesvirus, Herpesviridae Mule deerpox virus, Poxviridae Murine adenovirus 2, Adenoviridae Z murine adenovirus 1, Adenoviridae Murine hepatitis virus, Coronaviridae Murine herpesvirus, Herpesviridae Murine leukemia virus, Retroviridae Murine parainfluenza virus 1, Paramyxoviridae Murine poliovirus, Picornaviridae Murine polyomavirus, Papovaviridae Murray Valley encephalitis virus, Flaviviridae Nairobi sheep disease virus, Bunyaviridae Ovine adeno-associated virus, Parvoviridae Ovine adenoviruses 1 to 6, Adenoviridae Ovine astrovirus 1, Astroviridae Ovine herpesvirus 1, Herpesviridae Ovine herpesvirus 2, Herpesviridae Ovine pulrnonary adenocarcinoma virus, Retroviridae Patas monkey herpesvirus pH delta, Herpesviridae Penguinpox virus, Poxviridae Pneumonia virus of mice, Paramyxoviridae Porcine adenoviruses 1 to 6, Adenoviridae Porcine astrovirus 1, Astroviridae Porcine circovirus, Circoviridae Porcine enteric calicivirus, Caliciviridae Porcine enterovirus 1 to 11, Picornaviridae Porcine epidemic diarrhea virus, Coronaviridae Porcine hemagglutinating encephalomyelitis virus, Coronaviridae Porcine parvovirus, Parvoviridae Porcine respiratory and reproductive syndrome, Arterivirus Porcine rubulavirus, Paramyxoviridae Porcine transmissible gastroenteritis virus, Coronaviridae Porcine type C oncovirus, Retroviridae Porpoise distemper virus, Paramyxoviridae Primate calicivirus, Caliciviridae Rabbit coronavirus, Coronaviridae Rabbit fibroma virus, Poxviridae Rabbit hemorrhagic disease virus, Caliciviridae Rabbit kidney vacuolating virus, Papovaviridae Rabbit oral papillomavirus, Papovaviridae Rabbitpox virus, Poxviridae Rabies virus, Rhabdoviridae Raccoon parvovirus, Parvoviridae Raccoonpox virus, Poxviridae Red deer herpesvirus, Herpesviridae Red kangaroopox virus, Poxviridae Reindeer herpesvirus, Herpesviridae Reindeer papillomavirus, Papovaviridae Reovirus 1, Reoviridae Reovirus 2, Reoviridae Reovirus 3, Reoviridae Reticuloendotheliosis virus, Retroviridae Rhesus HHV-4-like virus, Herpesviridae Rhesus leukocyte associated herpesvirus strain 1, Herpesviridae Rhesus monkey cytomegalovirus, Herpesviridae Rhesus monkey papillomavirus, Papovaviridae Rubella virus, Togaviridae Sealpox virus, Poxviridae Sendai virus, Paramyxoviridae Sheep associated malignant catarrhal fever of, Herpesviridae Sheep papillomavirus, Papovaviridae Sheep pulmonary adenomatosis associated herpesvirus, Herpesviridae Sheeppox virus, Poxviridae Simian adenoviruses 1 to 27, Adenoviridae Simian agent virus 12, Papovaviridae Simian enterovirus 1 to 18, Picornaviridae Simian foamy virus, Retroviridae Simian hemorrhagic fever virus, Arterivirus Simian hepatitis A virus, Picornaviridae Simian immunodeficiency virus, Retroviridae Simian parainfluenza virus 10, Paramyxoviridae Simian parainfluenza virus 41, Paramyxoviridae Simian parainfluenza virus 5, Paramyxoviridae Simian rotavirus SA11, Reoviridae Simian sarcoma virus, Retroviridae Simian T-lymphotropic virus, Retroviridae Simian type D virus 1, Retroviridae Simian vancella herpesvirus, Herpesviridae Simian virus 40, Papovaviridae Sindbis virus, Togaviridae Skunkpox virus, Poxviridae Spider monkey herpesvirus, Herpesviridae Squirrel fibroma virus, Poxviridae Squirrel monkey herpesvirus, Herpesviridae Squirrel monkey retrovirus, Retroviridae Swine cytomegalovirus, Herpesviridae Swine infertility and respiratory syndrome virus, Arterivirus Swinepox virus, Poxviridae Tree shrew adenovirus 1, Adenoviridae Tree shrew herpesvims, Herpesviridae Vaccinia subspecies, Poxviridae Vaccinia virus, Poxviridae Varicella-zoster virus 1, Herpesviridae Vesicular stomatitisAlagoas virus, Rkabdoviridae Vesicular stomatitis Indiana virus, Rhabdoviridae Vesicular stomatitis New Jersey virus, Rhabdoviridae West Nile virus, Flaviviridae Western equine encephalitis virus, Togaviridae Woodchuck hepatitis B virus, Hepadnaviridae Woodchuck herpesvirus marmota 1, Herpesviridae Woolly monkey sarcoma virus, Retroviridae Yaba monkey tumor virus, Poxviridae Yellow fever virus, Flaviviridae

3. Other Infectious Agents

In addition to viruses, other infectious agents may also be targeted according to the present invention. These include bacteria, set forth in Table 2, as well as molds, fungi and parasites.

TABLE 2 BACTERIA Bacillus spp. Bacteroides fragilis Bordetella bronchiseptica Bordetella parapertussis Bordetella pertussis Bordetella pertussis Borrelia burgdorferi Branhamella (Moraxella) catarrhalis Branhamella (Moraxella) catarrhalis Branhamella (Moraxella) catarrhalis (non β-lactamase producer) Branhamella (Moraxella) catarrhalis (non β-lactamase producer) Branhamella (Moraxella) catarrhalis (non β-lactamase producer) Branhamella (Moraxella) catarrhalis (non β-lactamase producer) Branhamella (Moraxella) catarrhalis (β-lactamase producer) Branhamella (Moraxella) catarrhalis (β-lactamase producer) Branhamella (Moraxella) catarrhalis (β-lactamase producer) Branhamella (Moraxella) catarrhalis (β-lactamase producer) Campylobacter jejuni Campylobacter jejuni Campylobacter pylori Campylobacter pylori Corynebacterium JK Corynebacterium JK Enterococcus faecalis Enterococcus faecalis Enterococcus faecalis Enterococcus faecalis Enterococcus faecium Enterococcus spp. Haemophilus ducreyi Haemophilus influenzae Haemophilus influenzae Haemophilus influenzae (non β-lactamase producer) Haemophilus influenzae (non β-lactamase producer) Haemophilus influenzae (β-lactamase producer) Haemophilus influenzae (β-lactamase producer) Haemophilus influenzae (penicillin susceptible) Haemophilus influenzae (penicillin resistant) Haemophilus parainfluenzae Legionella spp. Legionella pneumophila Legionella pneumophila Legionella pneumophila Listeria monocytogenes Listeria monocytogenes Listeria monocytogenes Mycoplasma hominis Mycoplasma hominis Mycoplasma pneumoniae Mycoplasma pneumoniae Neisseria gonorrhoeae Neisseria gonorrhoeae (non β-lactamase producer) Neisseria gonorrhoeae (non β-lactamase producer) Neisseria gonorrhoeae (β-lactamase producer) Neisseria gonorrhoeae (β-lactamase producer) Neisseria meningitidis Nocardia asteroides Staphylococcus aureus Staphylococcus aureus Staphylococcus aureus (penicillin susceptible) Staphylococcus aureus (penicillin susceptible) Staphylococcus aureus (penicillin resistant) Staphylococcus aureus (methicillin susceptible) Staphylococcus aureus (methicillin susceptible) Staphylococcus aureus (methicillin susceptible) Staphylococcus aureus (methicillin resistant) Staphylococcus aureus (methicillin resistant) Staphylococcus aureus (methicillin resistant) Staphylococcus aureus (methicillin resistant) Staphylococcus coagulase f Staphylococcus coagulase f Staphylococcus coagulase f (non β-lactamase producer) Staphylococcus coagulase f (β-lactamase producer) Staphylococcus epidermidis Staphylococcus haemolyticus Staphylococcus hominis Streptococcus agalactiae Streptococcus agalactiae Streptococcus pneumoniae Streptococcus pneumoniae Streptococcus pneumoniae Streptococcus pneumoniae Streptococcus pneumoniae Streptococcus pneumoniae Streptococcus pyogenes Streptococcus pyogenes Streptococcus pyogenes Streptococcus pyogenes Streptococcus spp. Streptococcus spp. Ureaplasma urealyticum Ureaplasma urealyticum Mycoplasma hominis Mycoplasma pneumoniae Staphylococcus aureus Ureaplasma urealyticum

B. Other Antigens (Non-Infectious Agents)

A variety of other antigens are contemplated for use in accordance with the present invention. For example, an autoantigen is usually a normal protein or complex of proteins (and sometimes DNA or RNA) that is recognized by the immune system of patients suffering from a specific autoimmune disease. These antigens should under normal conditions not be the target of the immune system, but due to mainly genetic and environmental factors the normal immunological tolerance for such an antigen has been lost in these patients. The following autoantigens are contemplated as targets for antibodies of the present invention: acetylcholine receptor, adenine nucleotide translocator (ANT), aromatic L-amino acid decarboxylase, asialoglycoprotein receptor, bactericidal/permeability-increasing protein (Bpi), calcium-sensing receptor, cholesterol side-chain cleavage enzyme (CYP11α), collagen type IV α₃ chain, cytochrome P450 2D6 (CYP2D6), desmin, desmoglein 1, desmoglein 3, f-actin, GM gangliosides, glutamate decarboxylase (GAD65), glutamate receptor (GLUR), H/K ATPase, 17-α-Hydroxylase (CYP17), 21-hydroxylase (CYP21), IA-2 (ICA512), insulin, insulin receptor, intrinsic factor type 1, leukocyte function-associated antigen (LFA-1), myelin-associated glycoprotein (MAG), myelin basic protein, myelin oligodendrocyte glycoprotein (MOG), myosin, p-80-coilin, pyruvate dehydrogenase complex-E2 (PDC-E2), sodium iodide symporter (NIS), SOX-10, thyroid and eye muscle shared protein, thyroglobulin, thyroid peroxidase, thyrotropin receptor, tissue transglutaminase, transcription coactivator p75, tryptophan hydroxylase, tyrosinase, tyrosine hydroxylase, ACTH, aminoacyl-tRNA histidyl synthetase, aminoacyl-tRNA synthetase (several), cardiolipin, carbonic anhydrase II, collagen (multiple types), centromere-associated proteins, DNA-dependent nucleosome-stimulated ATPase, fibrillarin, fibronectin, glucose-6-phosphate isomerase, β2-glycoprotein I (β2-GPI), golgin (95, 97, 160, 180), heat shock protein, hemidesmosomal protein 180, histone H2A-H2B-DNA, IgE receptor, keratin, myeloperoxidase, proteinase 3 (PR3), RNA polymerase I-III (RNP), signal recognition protein (SRP54), topoisomerase-I (Scl-70), tubulin, vimentin, C1 inhibitor, C1q, factor II, factor V, factor VII, factor VIII, factor IX, factor X, factor XI, factor XII, thrombin, vWF, 60-kDa Ro protein, glycoprotein IIb/IIIg and Ib/IX, oxidized LDL, amphiphysin, cyclin B1, DNA topoisomerase II, desmoplakin, gephyrin, Hu proteins, neuronal nicotinic acetylcholine receptor, p53, p62 (IGF-II mRNA-binding protein), recoverin, Ri protein, βIV spectrin, synaptotagmin, voltage-gated calcium channels, and yo protein.

Another antigen that can be used is a tumor antigen. Tumor antigens are those antigens that are presented by MHC I or MHC II molecules on the surface of tumor cells. These antigens can sometimes be presented only by tumor cells and never by the normal ones. In this case, they are called tumor-specific antigens (TSAs) and typically result from a tumor specific mutation. More common are antigens that are presented by tumor cells and normal cells, and they are called tumor-associated antigens (TAAs). Cytotoxic T lymphocytes that recognized these antigens may be able to destroy the tumor cells before they proliferate or metastasize. Tumor antigens can also be on the surface of the tumor in the form of, for example, a mutated receptor, in which case they will be recognized by B-cells. Tumor antigens include the MAGE (1-10) and BAGE proteins, MUC-1, CEA, 17-1A, TRP-2, M-urinary antigen, M-fetal antigen, UTAA, GM2 ganglioside, GD2 ganglioside, hTRT, cytokeratin 19, SCCA-1 and -2, Orf73, PSA, CA 19-9, CA 72-4, CA 195, CA 55.1, NOVA2, CA 125, ART1, CASA, and CO-029.

Another group of antigen targets involve signaling proteins found in humans and other animals. These include cytokine receptors and the corresponding cytokines, growth factors and their corresponding receptors, and chemokines and their corresponding receptors. Included are inteferons α, β and γ, interleukins (IL-1α, -1β, -2, -3, -4, -5, -6, -7, -8, -9, -10, -11, -12, -13, -14, -15, -16, -17, -18, -19, -20, -21, -22, -23, LIF), GM-CSF, G-CSF, TGF-α, IGF-I, IGF-II, TGF-β, BMP, VEGF, EPO, NGF, BDNF, PDGF, neutrophins, TPO, GDF-8, GDF-9, bFGF, EGF, HGF, CCL1, CCL2, CCL3, CCL4, CCL5, CCL6, CCL7, CCL8, CCL9/10, CCL11, CCL12, CCL13, CCL14, CCL15, CCL16, CCL17, CCL18, CCL19, CCL20, CCL21, CCL22, CCL23, CCL24, CCL25, CCL26, CCL27, CXCL1, CXCL2, CXCL3, CXCL4, CXCL5, CXCL6, CXCL7, CXCL8, CXCL9, CXCL10, CXCL11, CXCL12, CXCL13, CXCL14, CXCL15, CXCL16, CXCL17, XCL1, XCL2, CX3CL1, and receptors for each of the foregoing ligands.

II. PREPARING HUMAN MONOCLONAL ANTIBODIES FROM IgM⁺ B-CELLS

The following are descriptions of the general procedures by which one can obtain human monoclonal antibodies. These procedures are exemplary and may be modified while retaining the essential aspects of the invention.

A. Obtaining IgM B-Cell Populations

To prepare B-cells from tonsils, tonsil tissue is mixed with antibiotic, chopped and minced to approximately 1 mm³ pieces, followed by gentle grinding of tonsil pieces and straining through a nylon strainer. The suspension is then centrifuged on a Ficoll cushion. The boundary layer containing mononuclear cells is extracted, washed and re-suspended in DPBS. Further enrichment (>95%) can be achieved by negative selection using antibodies and magnetic beads

To prepare B-cells from peripheral blood, venous blood is drawn into syringes containing heparin sodium to which prevent coagulation, diluted, centrifuged on a Ficoll cushion, collected and stored in aliquots. The boundary layer containing mononuclear cells is extracted, washed and re-suspended in DPBS. Further enrichment can be achieved as stated above.

B. EBV Immortalization

For infection by inoculation with EBV supernatant, B-cells are resuspended at 10⁶ to 10⁷ cells per ml in complete RPMI media, and mixed with an equal volume of filtered EBV supernatant, then incubated for 4 hours at 37° C. and 5% CO₂. The culture volume may be adjusted by the addition of complete RPMI media, such that infected cells were resuspended for cell culture at a desired concentration (generally 10⁵ to 10⁶ cells per ml). Cells are then dispensed into multi-well plates and transferred to a tissue culture incubator at 37° C. and 5% CO₂.

For spinfection, B-cells are resuspended at 10⁶ to 10⁷ cells per ml in complete RPMI media, and mixed with an equal volume of 10-fold ultrafiltration concentrated EBV and placed in a well of a 6-well tissue culture plate. The plate is then centrifuged at 900 g for 1 hr at ambient temperature, at which time infected cells are re-suspended in complete RPMI media at a desired concentration (generally 10⁵ to 10⁶ cells per ml), dispensed into multi-well plates and transferred to a tissue culture incubator at 37° C. and 5% CO₂.

Optionally, B-cells may be contacted with Toll Like Receptor (TLR) ligands at the time of or subsequent to the infection. The ligands may be added at the following final concentrations: Pam3CSK4 (0.5 μg/ml), Zymoson (1 μg/ml), poly I:C (25 μg/ml), LPS (5 μg/ml), Imiquinoid (1 μg/ml), and CpG (1 μg/ml).

Infectivity varies based upon route of infection. Infection of tonsil B cells by inoculation with EBV supernatant results in immortalization of approximately 1-5% of B cells. Addition of TLR ligands approximately doubles infection efficiency. Infection of tonsil B cells by spinfection with concentrated virus increases infection efficiency to virtually 100% after 24 hours.

C. Culturing to Induce Immunoglobulin Isotype Class Switching

To induce B-cell differentiation and immunoglobulin isotype class switching, cytokines and other signaling agents are added to EBV infected B-cells immediately after infection, 16 to 20 hr after infection, and/or sequentially at weekly intervals (2, 3, 4 or 5 times). Agents may be diluted in media and added to cells at the following final concentrations: recombinant human interleukins (IL) IL-4, 0.2 ng/ml; IL-5, 0.2 ng/ml; IL-6, 0.1 ng/ml; IL-9, 0.2 ng/ml; IL-10, 0.24 ng/ml; IL-13, 1 ng/ml; recombinant human interferon-α2a (IFN-α2a), 2,000 IU/ml; recombinant human BAFF, 1 ng/ml; recombinant human soluble CD40L, 5 ng/ml; goat anti-human IgM F(ab′)₂, 1.4 μg/ml (amounts are approximate). Particular combinations comprise anti-IgM F(ab′)₂, CD40L+/−BAFF; anti-IgM F(ab′)₂ and BAFF; CD40L+/−BAFF; anti-IgM F(ab′)₂ and IL-6+/−IL4; and anti-IgM F(ab′)₂ and IL-9+/−IL-13.

The initiation of immunoglobulin isotype class switching begins from about 7 to about 10 days following exposure to the cytokine/growth factor/signaling agent cocktail, and the process continues for the following 10 days.

D. Selection of Immortalized B-Cells

Following collection, culture supernatants are collected once a week from tonsil and blood B-cell cultures, pooled, and tested using an ELISA or other screening format, such as dot blot, or flow cytometry. Antigen may be layered on the wells of a polystyrene (e.g., 96-well) plate and allowed to bind, e.g., overnight. Plates are then washed, blocked, and contacted with immortalized B cell culture supernatant samples or controls in triplicate or other replicates. Subsequently, the plate is washed extensively, and then e.g., alkaline phosphatase (AP)-coupled goat anti-human IgG or other antibody is added for detection of bound IgG by AP conversion of colorimetric substrate p-nitrophenyl phosphate disodium salt.

Based upon the discussion above, immunoglobulin isotype class switching starts at about 7 days following exposure to the cytokine/growth factor/signaling agent cocktail. Thus, from about 7-21 days, about 10-21, about 7-10 days or about 10-14 days, or at 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or 21 days, one will select B-cells that have undergone immunoglobulin isotype class switching and thus predominantly secrete IgG.

III. CLONING AND EXPRESSION OF HUMAN IMMUNOGLOBULIN LIGHT AND HEAVY CHAINS

Various methods may be employed for the cloning and expression of human immunoglobulin light and heavy chain sequences. Weltschof et al. (1995), incorporated herein by reference, describes in detail the methods used by the inventors. The variable regions, or variable+constant regions, may be cloned.

Other techniques, such as those described by Takekoshi et al. (2001), are also useful. In that reference, total cellular RNA was isolated from pelleted cells using a commercial kit (RNeasy mini kit, Qiagen). Using random 9-mers, nucleotides and reverse transcriptase (Takara, RNA-PCR kit, Ohtsu), cDNAs were synthesized and were amplified by the polymerase chain reaction (PCR), with heavy and light chain primers specific for human immunoglobulins (Ig). A “touchdown” PCR protocol was employed, i.e., three cycles each of denaturation at 95° C. for 1 min, annealing for 1 min, and elongation at 72° C. for 2 min, for a total of 11 cycles. The annealing temperature was varied from 65-55° C. in steps of 1° C. The touchdown cycles were followed by 25 cycles using an annealing temperature of 55° C. The resultant PCR product was gel-purified in agarose and extracted using Qiaquick spin-columns (Qiagen). The light chain and heavy chain Fc genes were then cloned into the NheI/AscI and the SfiI/NotI sites of the expression vector pFab1-His2. The ligated pFab1-His2 vectors with the light chain (K and X) and Fc heavy chain genes (γ and μ) were introduced into competent E. coli JM109 cells (Toyobo, Osaka). After transformation, the E. coli cells were plated onto Luria-Bertani (LB)/ampicillin (50 μg/ml) plates. Isolated bacterial colonies were incubated at 30° C. in 2 ml of Super Broth (SB) with ampicillin (50 μg/ml) and MgCl₂ (1.5 mM). Isopropyl-β-D-thiogalactopyranoside (IPTG) was used to induce production of the Fab protein. Cells from the bacterial cultures were pelleted, resuspended in 0.3 ml of B-PER (Pierce) with a protease inhibitor cocktail (Complete, Boehringer Mannheim), and shaken for 5 min at room temperature. Cell lysates were centrifuged at 15,000 G for 10 min, and the resultant supernatant containing the Fab antibody portion was collected.

The foregoing is purely exemplary and other methods may be employed.

IV. ANTIBODY PRODUCTION

Once cloned, the nucleic acids for the human light and heavy chains will be inserted into appropriate expression vectors and transferred into host cells (e.g., antibody-producing cells) that will support production of antibodies. Particular cell lines contemplated for production are 293 cells, CHO cells, COS cells or various forms of myeloma cells, some lacking IgG. These cells may be exploited for human MAb production in two basic ways. First, myelomas or immortalized cells can be injected (often into the peritoneal cavity) into a histocompatible animal of the type that was used to provide the somatic and myeloma cells for the original fusion (e.g., a syngeneic mouse), or into an immunodeficient animal for injection of noncompatible cells. Optionally, the animals are primed with a hydrocarbon, especially oils such as pristane (tetramethylpentadecane) prior to injection. The injected animal develops tumors secreting the specific monoclonal antibody produced by the transfected myeloma. The body fluids of the animal, such as serum or ascites fluid, can then be tapped to provide human MAbs in high concentration. Second, the individual cell lines could be cultured in vitro, where the human MAbs are naturally secreted into the culture medium from which they can be readily obtained in high concentrations.

Human MAbs produced by either means may be further purified, if desired, using filtration, centrifugation and various chromatographic methods such as HPLC or affinity chromatography. Fragments of the monoclonal antibodies of the invention can be obtained from the monoclonal antibodies so produced by methods which include digestion with enzymes, such as pepsin or papain, and/or by cleavage of disulfide bonds by chemical reduction.

V. DIAGNOSTICS

The present invention contemplates the use of human monoclonal antibodies in in vivo diagnostic procedures. Cancers, for example, are advantageously detected using antibodies that, if human in origin, can be administered systemically. “Detectable labels” are compounds and/or elements that permit detection of bound antibody. Many appropriate imaging agents are known in the art, as are methods for their attachment to antibodies (see, for e.g., U.S. Pat. Nos. 5,021,236; 4,938,948; and 4,472,509, each incorporated herein by reference). The imaging moieties used can be paramagnetic ions; radioactive isotopes; fluorochromes; NMR-detectable substances; X-ray imaging.

In the case of paramagnetic ions, one might mention by way of example ions such as chromium (III), manganese (II), iron (III), iron (II), cobalt (II), nickel (II), copper (II), neodymium (III), samarium (III), ytterbium (III), gadolinium (III), vanadium (II), terbium (III), dysprosium (III), holmium (III) and/or erbium (III), with gadolinium being particularly preferred. Ions useful in other contexts, such as X-ray imaging, include but are not limited to lanthanum (III), gold (III), lead (II), and especially bismuth (III).

In the case of radioactive isotopes for therapeutic and/or diagnostic application, one might mention astatine²¹¹, ¹⁴carbon, ⁵¹chromium, ³⁶chlorine, ⁵⁷cobalt, ⁵⁸cobalt, copper⁶⁷, ¹⁵²Eu, gallium⁶⁷, ³hydrogen, iodine¹²³, iodine¹²⁵, iodine¹³¹, indium¹¹¹, ⁵⁹iron, ³²phosphorus, rhenium¹⁸⁶, rhenium¹⁸⁸, ⁷⁵selenium, ³⁵sulphur, technicium^(99m) and/or yttrium⁹⁰. ¹²⁵I is often being preferred for use in certain embodiments, and technicium^(99m) and/or indium¹¹¹ are also often preferred due to their low energy and suitability for long range detection. Radioactively labeled monoclonal antibodies of the present invention may be produced according to well-known methods in the art. For instance, monoclonal antibodies can be iodinated by contact with sodium and/or potassium iodide and a chemical oxidizing agent such as sodium hypochlorite, or an enzymatic oxidizing agent, such as lactoperoxidase. Monoclonal antibodies according to the invention may be labeled with technetium^(99m) by ligand exchange process, for example, by reducing pertechnate with stannous solution, chelating the reduced technetium onto a Sephadex column and applying the antibody to this column. Alternatively, direct labeling techniques may be used, e.g., by incubating pertechnate, a reducing agent such as SNCl₂, a buffer solution such as sodium-potassium phthalate solution, and the antibody. Intermediary functional groups which are often used to bind radioisotopes which exist as metallic ions to antibody are diethylenetriaminepentaacetic acid (DTPA) or ethylene diaminetetracetic acid (EDTA).

Among the fluorescent labels contemplated for use as conjugates include Alexa 350, Alexa 430, AMCA, BODIPY 630/650, BODIPY 650/665, BODIPY-FL, BODIPY-R6G, BODIPY-TMR, BODIPY-TRX, Cascade Blue, Cy3, Cy5,6-FAM, Fluorescein Isothiocyanate, HEX, 6-JOE, Oregon Green 488, Oregon Green 500, Oregon Green 514, Pacific Blue, REG, Rhodamine Green, Rhodamine Red, Renographin, ROX, TAMRA, TET, Tetramethylrhodamine, and/or Texas Red.

Another type of antibody conjugates contemplated in the present invention are those intended primarily for use in vitro, where the antibody is linked to a secondary binding ligand and/or to an enzyme (an enzyme tag) that will generate a colored product upon contact with a chromogenic substrate. Examples of suitable enzymes include urease, alkaline phosphatase, (horseradish) hydrogen peroxidase or glucose oxidase. Preferred secondary binding ligands are biotin and/or avidin and streptavidin compounds. The use of such labels is well known to those of skill in the art and are described, for example, in U.S. Pat. Nos. 3,817,837; 3,850,752; 3,939,350; 3,996,345; 4,277,437; 4,275,149 and 4,366,241; each incorporated herein by reference.

Several methods are known in the art for the attachment or conjugation of an antibody to its conjugate moiety. Some attachment methods involve the use of a metal chelate complex employing, for example, an organic chelating agent such a diethylenetriaminepentaacetic acid anhydride (DTPA); ethylenetriaminetetraacetic acid; N-chloro-p-toluenesulfonamide; and/or tetrachloro-3α-6α-diphenylglycouril-3 attached to the antibody (U.S. Pat. Nos. 4,472,509 and 4,938,948, each incorporated herein by reference). Monoclonal antibodies may also be reacted with an enzyme in the presence of a coupling agent such as glutaraldehyde or periodate. Conjugates with fluorescein markers are prepared in the presence of these coupling agents or by reaction with an isothiocyanate. In U.S. Pat. No. 4,938,948, imaging of breast tumors is achieved using monoclonal antibodies and the detectable imaging moieties are bound to the antibody using linkers such as methyl-p-hydroxybenzimidate or N-succinimidyl-3-(4-hydroxyphenyl)propionate.

Yet another known method of site-specific attachment of molecules to antibodies comprises the reaction of antibodies with hapten-based affinity labels. Essentially, hapten-based affinity labels react with amino acids in the antigen binding site, thereby destroying this site and blocking specific antigen reaction. However, this may not be advantageous since it results in loss of antigen binding by the antibody conjugate.

Molecules containing azido groups may also be used to form covalent bonds to proteins through reactive nitrene intermediates that are generated by low intensity ultraviolet light (Potter & Haley, 1983). In particular, 2- and 8-azido analogues of purine nucleotides have been used as site-directed photoprobes to identify nucleotide binding proteins in crude cell extracts (Owens & Haley, 1987; Atherton et al., 1985). The 2- and 8-azido nucleotides have also been used to map nucleotide binding domains of purified proteins (Khatoon et al., 1989; King et al., 1989; and Dholakia et al., 1989) and may be used as antibody binding agents.

VI. PASSIVE IMMUNIZATION

A. Administration

A major advantage of passive antibody immunization is that it immediately provides a state of immediate immunity that can last for weeks and possibly months. Some human IgG isotypes have serum half-lives in excess of 30 days, which would confer long-lived protection to passively immunized persons. Antibodies are natural products with minimal toxicity, provided that they contain no aggregates and have no reactivity with host tissues. Also, since active vaccines are available, simultaneous administration of vaccine and antibody may be possible to provide both immediate and long-lasting protection (e.g., for rabies in post-exposure prophylaxis).

Administration of MAbs produced as described above will follow the general protocols for passive immunization. Although passive antibodies are generally given systemically, oral administration can be useful against certain gastrointestinal agents. While many antibody preparations in clinical use are given intravenously, novel monoclonal antibodies used therapeutically for autoimmune disease are often administered subcutaneously, and injection of gamma-globulin for hepatitis prophylaxis was traditionally administered intra-muscularly. The need for intravenous administration is a severe constraint for mass passive immunization and would likely limit this practice to a few recipients. However, this disadvantage may potentially be circumvented because Ig preparations can theoretically be administered intramuscular, subcutaneous, intralesional, or even intraperitoneal routes. Hence, generating antibody preparations suitable for delivery into one of the large muscles of the arm, leg or buttock, or into the subcutaneous fat in the stomach or thigh, may be possible without the need for logistically complicated intravenous infusions. The present invention is ideally suited to provide this option, as antibody preparations for these routes of administration would require high specificity, permitting administration in a relatively small volume.

B. Pharmaceutical Compositions

It is envisioned that, for administration to a host, MAbs will be suspended in a formulation suitable for administration to a host. Aqueous compositions of the present invention comprise an effective amount of an antibody dispersed in a pharmaceutically acceptable formulation and/or aqueous medium. The phrases “pharmaceutically and/or pharmacologically acceptable” refer to compositions that do not produce an adverse, allergic and/or other untoward reaction when administered to an animal, and specifically to humans, as appropriate.

As used herein, “pharmaceutically acceptable carrier” includes any solvents, dispersion media, coatings, antibacterial and/or antifungal agents, isotonic and/or absorption delaying agents and the like. The use of such media or agents for pharmaceutical active substances is well known in the art. Except insofar as any conventional media or agent is incompatible with the active ingredient, its use in the therapeutic compositions is contemplated. Supplementary active ingredients can also be incorporated into the compositions. For administration to humans, preparations should meet sterility, pyrogenicity, general safety and/or purity standards as required by FDA Office of Biologics standards.

Antibodies will generally be formulated for parenteral administration, e.g., formulated for injection via the intravenous, intramuscular, subcutaneous, intralesional, or even intraperitoneal routes. The preparation of an aqueous composition that contains cells as a viable component or ingredient will be known to those of skill in the art in light of the present disclosure. In all cases the form should be sterile and must be fluid to the extent that easy syringability exists and that viability of the cells is maintained. It is generally contemplated that the majority of culture media will be removed from cells prior to administration.

Generally, dispersions are prepared by incorporating the various soluble receptors, antibodies, inhibitory factors, or viable cells into a sterile vehicle which contains the basic dispersion medium and the required other ingredients for maintaining cell viability as well as potentially additional components to effect proliferation or differentiation in vivo. Upon formulation, solutions will be administered in a manner compatible with the dosage formulation or in such amount as is therapeutically effective. Some variation in dosage will necessarily occur depending on the condition of the subject being treated. The person responsible for administration will, in any event, determine the appropriate dose for the individual subject.

VII. EXAMPLES

The following examples are included to demonstrate preferred embodiments of the invention. It should be appreciated by those of skill in the art that the techniques disclosed in the examples which follow represent techniques discovered by the inventor to function well in the practice of the invention, and thus can be considered to constitute preferred modes for its practice. However, those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the spirit and scope of the invention.

Example 1 Materials & Methods for B-Cells Reactive to H5 HA

Isolation and culture of tonsil B cells. To prepare B cells from tonsils, tonsil tissue was placed inside a sterile Petri dish (VWR International, cat. #25384-088) containing 20-30 ml Dulbecco's phosphate buffered saline (DPBS, without CaCl₂ or MgCl₂; Gibco/Invitrogen, Grand Island, N.Y. cat. #14190144) supplemented with 1× Antibiotic-Antimycotic (Gibco/Invitrogen cat. #15240-062). The tissue was chopped and minced with scalpels to approximately 1 mm³ pieces. Additional lymphocytes were released by gentle grinding of tonsil pieces between the frosted glass surfaces of two sterile microscope slides (VWR cat. #12-550-34), and single cell preparation was made by straining through 70 μm nylon strainer (BD Falcon, cat. #352350, BD Biosciences, Two Oak Park, Bedford, Mass.). This suspension was layered onto a Ficoll (Amersham Biosciences cat. #17-1440-03, Uppsala, Sweden) cushion (35 ml sample over 15 ml Ficoll) and resolved at 1500 G for 20 min. The boundary layer containing mononuclear cells was extracted, washed 2× with DPBS (1300 G for 7 min), counted, and re-suspended in DPBS at 10⁸ cells/ml. A highly enriched (>95%) B-cell population was obtained with the use of StemSep Negative Selection Human B-cell Enrichment Kit antibody cocktail (cat. #14064A) and magnetic beads (cat. #19150) from StemCell Technologies Inc., Vancouver, Canada, according to manufacturer's instructions, with the following modifications for use on a “The Big Easy” EasySep magnet (StemCell Tech. cat. #18001). All steps were performed in a laminar flow biohazard hood at ambient temperature. The cell suspension was placed in a sterile round bottom 14 ml polypropylene tube (VWR cat. #60818-689), mixed with an equal volume of the StemSep Negative Selection Human B-cell Enrichment Kit antibody cocktail, and incubated for 10 minutes. Then, a volume of magnetic bead suspension equal to the antibody cocktail volume was added, followed by 10 minute incubation. The volume inside the tube was brought to 10 ml with DPBS and the tube (minus the cap) was placed inside the magnet for 10 minutes, at which time the contents of the tube (still inside the magnet) were gently decanted in a single pour into a second sterile 14 ml tube. The original tube with non-B cells adhering to its walls was removed from the magnet, and the second tube was inserted for 10 minute clean-up incubation. The enriched B-cell suspension obtained after the first and second negative selection steps was poured into a 15 ml Falcon tube, counted, washed with DPBS (1300 G for 7 min) and resuspended in an appropriate volume of complete RPMI media for in vitro culture (generally 10⁵ to 10⁶ cells/ml) in a 37° C., 5% CO₂ tissue culture incubator. Complete RPMI media contains RPMI 1640 (Gibco/Invitrogen cat. #11875-093) supplemented with 10% fetal bovine serum (FBS, HyClone cat. #SH30088.03, lot. #AQC23460, Logan, Utah), and 100 U/ml Penicillin, 100 μg/ml Streptomycin (cat. #15140-122), 2 mM L-Glutamine (cat. #25030-081), 1 mM Sodium Pyruvate (cat. #11360-070), 10 mM HEPES (cat. #15630-080), 0.1% 2-mercaptoethanol (cat. #21985.023), and 0.1% Falk's Cloning Cocktail, which consists of 50 mM α-thioglycerol (Sigma, cat.# M6145), 20 μM bathocuproinedisulfonic acid (Sigma, cat. #B1125), 100 mM Na pyruvate (cat. #11360-070), 1M HEPES pH 7.4 (cat. #15630-080). L-glutamine, Sodium Pyruvate, Penicillin/Streptomycin and HEPES were obtained from Gibco/Invitrogen.

Isolation and culture of peripheral blood B cells. To prepare B cells from peripheral blood, venous blood (up to 180 ml) was drawn into 60 ml syringes containing 1-5 ml citric acid or heparin sulfate, which prevent coagulation, diluted with equal volume of DPBS, layered onto a Ficoll cushion (35 ml of diluted sample over 15 ml Ficoll) and resolved at 2000 rpm for 20 min. Serum (from upper layer) was collected and stored in aliquots. The boundary layer containing mononuclear cells was extracted, washed 2× with DPBS (1300 G for 7 min), counted, and re-suspended in DPBS at 10⁸ cells/ml. Highly pure populations of B-cells were obtained with the use of StemSep Negative Human B-cell Enrichment Kit (StemCell Technologies Inc.) as described above for isolation of peripheral blood B-cells. Isolated B-cells were washed (1300 G for 7 min) and re-suspended at 10⁵-10⁶ cells per ml of complete RPMI media (described above), and cultured in a 37° C., 5% CO₂ tissue culture incubator.

EBV stock preparation. To prepare infectious Epstein-Barr virus (EBV) stocks, B95-8 cells, a marmoset lymphoblastoid cell line (LCL) chronically infected with B95-8 strain EBV (Miller & Lipman, 1973), or EBfaV-GFP cells (Speck et al., 1999; described below), were cultured in complete RPMI media (described above) at a cell density of approximately 10⁵ cells/ml, in a 37° C., 5% CO₂ tissue culture incubator. EBfaV-GFP cells were derived from B95-8 cells, where the EBV genome was modified by homologous recombination, deleting the LMP2a gene and replacing it with enhanced green fluorescence protein (EGFP) (under control of the CMV immediate/early promoter) as well as neomycin resistance (neo^(R)) genes (Speck et al., 1999). These cells contain a mixture of EBfaV-GFP (LMP2a⁻ EGFP⁺) genomes and wild-type B95-8 genomes.

Approximately 140 ml of cell culture (containing either B95-8 EBV or recombinant EBfaV-GFP) was induced to enter lytic virus production phase by treatment with phorbol myristate acetate (PMA, 10 ng/ml, Calbiochem, cat. #524400). After a four hour incubation with PMA, the PMA was removed from the culture supernatant and replaced with complete RPMI media. The cells were cultured for 3 to 4 days until highly confluent, at which point cells were removed by centrifugation (1300 G for 7 min), and culture supernatant was filtered through 150 ml Nalgene 0.45 μm vacuum filter (Corning cat. #430320). Filtered supernatant was either flash-frozen in liquid nitrogen in 1.4 ml aliquots for storage at −80° C. in 1.5 ml Eppendorf tubes, or concentrated by ultrafiltration as described below.

EBV concentration. Viral concentration was performed by loading the filtered supernatant into two Centricon Plus-70 (100K MW cut-off) units (Millipore, Billerica, Mass.) and concentrated according to manufacturer's instructions. The filter units were centrifuged (2000 G) for between 15 and 45 minutes (monitored each 15 minutes), until the minimal retentate volume (approximately 0.5 ml per filtration unit) was achieved. The filtrate was discarded, and virus-containing concentrates were re-suspended with complete RPMI media up to a total volume of 14 ml (or 1/10 of the original culture supernatant volume). One ml aliquots were transferred into cryovials, flash-frozen in liquid nitrogen, and transferred to −80° C. freezer for storage.

B cell infection by inoculation. B cells were resuspended at 10⁶ to 10⁷ cells/ml in complete RPMI media, and were mixed with an equal volume of filtered EBV supernatant, then placed in a T-25 flask and incubated for 4 hours in a tissue culture incubator at 37° C. and 5% CO₂. The culture volume was then adjusted by the addition of complete RPMI media, such that infected cells were resuspended for cell culture at the desired concentration (generally 10⁵ to 10⁶ cells per ml), dispensed into multi-well plates and transferred to a tissue culture incubator at 37° C. and 5% CO₂.

B cell infection by spinfection with concentrated EBV stocks. B cells were resuspended at 10⁶ to 10⁷ cells/ml in complete RPMI media, and were mixed with an equal volume of concentrated EBV and placed in a well of a 6-well tissue culture plate (Greiner bio-one, cat. #65760). The plate was then centrifuged at 900 G for 1 hour at ambient temperature, at which time infected cells were re-suspended in complete RPMI media at a desired concentration (generally 10⁵ to 10⁶ cells per ml), dispensed into multi-well plates and transferred to a tissue culture incubator at 37° C. and 5% CO₂.

Infection in the presence of TLR ligands. B cells were infected with B95-8 strain EBV as described above, with the addition of Toll-Like Receptor (TLR) ligands at the time of the infection. The ligands were added at the following final concentrations: lipoprotein Pam3-CSK4 (0.5 μg/ml), zymosan (Zymoson) (1 μg/ml), polyinosine, polycitadylic acid (poly I:C) (25 μg/ml), lipopolysaccharide (LPS) (5 μg/ml), Imiquimod (1 μg/ml), unmethylated CpG DNA (1 μg/ml). All TLR ligands (from InVivogen Inc) were generously donated by Dr. Mohamed Salem (MUSC).

Evaluation of B cell immortalization efficiency by lymphoblastoid cell outgrowth. At 12 hours post-infection, B cells were counted and dispensed into wells of 96-well round bottom plates (Greiner cat#650180) as a 2-fold dilution series, with each consecutive row of wells containing half the number of cells found in the previous row. The initial rows contained 50,000 cells per well, and final rows in the dilution series contained 24 cells per well. Cells were incubated for 9 days in a tissue culture incubator at 37° C. and 5% CO₂, at which point lymphoblastoid cell outgrowth was visible by microscopy. Immortalization efficiency was estimated based upon the assumption that lymphoblastoid cell proliferation resulted from EBV immortalization of at least one B cell in the well. Thus, the efficiency was calculated from rows containing wells with the lowest number of cells per well in which lymphoblastoid cell proliferation was consistently observed by microscopy, and expressed as 1 immortalization event per number of cells originally dispensed into the well.

Evaluation of EBV-GFP infection efficiency of 293 cells. Because recombinant EBV-GFP virus contains the EGFP gene encoding enhanced green fluorescence protein in place of the latent membrane protein-2 (LMP2) gene, infection with the virus can be measured by fluorescence microscopy or by flow cytometry as early as 24 hours post-infection. 293 cells were infected by inoculation or by spinfection as follows. Cells were trypsinized, washed and resuspended in complete DMEM media, containing DMEM (Mediatech cat. #10-013-CM), 10% Cosmic Calf serum (CCS, HyClone cat. #HS0087.03, lot. #APE21241), Penicillin, 100 U/ml, Streptomycin, 100 μg/ml (Gibco/Invitrogen, cat. #15140-122), at 1×10⁶ cells/1 ml per well into 6-well plates. 1 ml of EBfaV-GFP virus stock, concentrated or un-concentrated, was added to the cells. Plates were either incubated overnight for inoculation or centrifuged for 1 hour at 900 G for spinfection. Infection efficiency was determined 48 hours post-infection by visual inspection using fluorescence microscopy.

Evaluation of EBfaV-GFP infection efficiency of B cells. To quantitatively evaluate B cell infection efficiency, tonsil B cells were dispensed into wells of a 96-well plate at 2×10⁵ cells/100 μl per well. TLR ligands were added to some of the wells at the concentrations previously described above, and cells were incubated for 4 hours at 37° C., 5% CO₂. Concentrated EBfaV-GFP virus stock (100 μl/well) was then added to all wells and the cells were infected by spinfection as previously described. Infection efficiency was analyzed by flow cytometry for EGFP⁺ cells 24 hours later.

Flow Cytometry analysis was performed using a Becton Dickinson FACSCalibur instrument at the MUSC Flow Cytometry Facility, according to established methods. Antibodies are listed in Table 3.

TABLE 3 Antibodies for B-Cell Characterization NAME FUNCTION EXPRESSION CD19 Assembles with the BCR in order Pantropic B cell marker to decrease the threshold for antigen-specific receptor-dependent stimulation CD20 B-cell surface molecule with a role Present on all B lymphocytes, except in the differentiation and plasma cells development of B-cells into plasma cells CD27 Member of the NGF/TNF receptor Marker for human somatically mutated, superfamily; present on germinal B-cells; found on both B and T center B-cells. Soluble CD27 is lymphocytes upon cell activation; produced by plasma B-cells upregulated on post-germinal B cells CD30 Transmembrane cytokine receptor Upregulated on post-germinal center belonging to the TNF receptor cells; present on Hodgkin's and Reed- superfamily; has a role in Sternberg cells and on tumor cells of regulating the function, anaplastic large cell lymphomas differentiation and/or proliferation of normal lymphoid cells CD38 Functions in cell adhesion, signal Expressed at multiple stages; first transduction and calcium signaling appears on bone marrow precursor cells, but is lost on mature lymphocytes; it protects germinal center cells from apoptosis, but memory cells exiting the germinal center lack CD38; present on terminally differentiated cells. IgD Immunoglobulin molecule with Present on the mature B-lymphocytes unknown function that have not initiated immunoglobulin isotype class switching and somatic hypermutation

Induction of B cell differentiation. To determine their effect on B cell differentiation during the immortalization process, cytokines and other signaling agents were added to EBV infected B cells either immediately after infection, or 16 to 20 hours after infection, and twice more at weekly intervals. All agents were diluted in complete RPMI media and added to cells at the following final concentrations: recombinant human interleukins (IL) IL-4, 0.2 ng/ml; IL-5, 0.2 ng/ml; IL-6, 0.1 ng/ml; IL-9, 0.2 ng/ml; IL-10, 2.4 ng/ml; IL-13, 1 ng/ml; recombinant human interferon-α (IFN-α2a), 2,000 IU/ml; recombinant human BAFF, 1 ng/ml; recombinant human soluble CD40L, 5 ng/ml; goat anti-human IgM (Fab′)₂, 1.4 μg/ml. IL-4 (cat. #200-04), IL-5 (cat. #200-05), IL-6 (cat. #200-06), IL-9 (cat. #200-09), IL-10 (cat. #200-10), IL-13 (cat. #200-13), CD40L (cat. #310-02) and BAFF (cat. #310-13) were obtained from PeproTech (Rocky Hill, N.J.). IFN-α2a (Roferon^(R)-A) was from Roche Pharmaceuticals, and goat anti-human IgM (Fab′)₂ (cat. #109-006-129) was from Jackson Immune Research Laboratories Inc.

Creation of immortalized B cell repertoires used in H5 hemagglutinin binding studies. Tonsil or peripheral blood B cells were infected by spinfection with concentrated B95-8 virus as described above. Immediately following spinfection, cells were resuspended in complete RPMI media to which IL-4 (0.2 ng/ml), IL-6 (0.1 ng/ml), BAFF (10 ng/ml), and goat anti-human IgM (Fab′)₂ (1.62 μg/ml) (for three samples) or CD40L (5 ng/mL), BAFF (10 ng/ml), and goat anti-human IgM (Fab′)₂ (1.62 μg/ml) (for five samples) were added.

Measurement of human immunoglobulin IgM and IgG production by ELISA. Culture supernatants (1 ml from each well of 24 well plates) were collected at various time points beginning 1 week after infection and stored frozen at −20° C. until assay. Thawed supernatants, 10 μl per sample, or 10 μl of standards consisting of purified human IgG (Sigma-Aldrich cat. #12511) or IgM (cat. #18260), were mixed with 90 μl of binding buffer consisting of 100 mM Na₂HP0₄, pH 9. Samples were then bound directly to quadruplicate wells of Nunc 96-well EasyWash plates (Costar cat. #3369). All samples were added to duplicate plates, one for detection of IgG, the other for detection of IgM. Plates were incubated at room temperature for 1 hour, washed 4 times with wash buffer consisting of PBST (80.0 g NaCl, 11.6 g Na₂HPO₄, 2.0 g KCl, 5 ml Tween-20, pH 7.0 in 10 L), and blocked with 2% BSA in wash buffer for 1 hour. Plate bound IgG and IgM were detected using alkaline phosphatase (AP) coupled goat anti-human IgG or IgM (Southern Biotech cat #2040-04 or 2020-04 respectively), 100 μl per well diluted 1:1,000 was added for 1 hour. After washing, AP conversion of colorimetric substrate p-nitrophenyl phosphate disodium salt (PNPP, Peirce cat #37620) was detected by measuring absorbance at OD₄₀₅ using a Multiskan Spectrum plate reader (ThermoLabsystems). Levels of human immunoglobulin in culture supernatant samples were calculated following standard curve calibration of purified human IgG and IgM standards using MultiSkan software.

Sample collection for H5 HA ELISA analysis. Culture supernatants were collected once a week from tonsil and peripheral blood immortalized B cell cultures (150 μl from each well, replaced with fresh RPMI plus CD40L, BAFF and anti-human IgM). After weeks 1 and 2, the supernatants were pooled by combining 25 μl of sample from each well on a plate. For week 3, pooled supernatants were generated from individual rows on each plate by combining 50 μl from each well in a specified row (A, B, C, etc.). Supernatant from the entire well was used for analysis when testing individual or pooled dual wells. Once an individual well secreting anti-H5 HA IgG had been identified, cells from that well were counted, and subcloned into at least four 96-well plates, each containing 1000, 100, 10 or 1 cell/well. After 2 weeks, sample collection and analysis of supernatants from plates, then rows, then wells were repeated. The goal of the subcloning strategy was to obtain H5 HA-reactive IgG from the wells initially plated with no more than 1 cell per well.

H5 HA ELISA. Purified recombinant H5 hemagglutinin (HA) from H5N1 avian influenza strain A/Vietnam/1203/2004 (Protein Sciences Corp) was diluted to 2 μg/ml in a high pH 100 mM sodium phosphate binding buffer (pH 9.0), dispensed at 50 μl per well into 96-well EasyWash plates (Costar cat. #3369), and allowed to bind overnight. To help control for non-specific plate binding in each sample, an equal number of wells received binding buffer only. Plates were then washed, and blocked with a neutral pH 100 mM sodium phosphate buffer (pH 7.2) containing 2% BSA. Culture supernatant from samples or controls 100 μl per well was added in triplicate.

Controls included serum from healthy human volunteers, diluted 1:500 with complete RPMI media; purified human IgG (Sigma) and Rituxan^(R) (a humanized anti-CD20 IgG1 monoclonal antibody, Genentech, San Francisco, Calif. 94080, cat. #50242-051-21, lot #M70267) diluted to 5 μg/ml in complete RPMI media. Subsequently, the plate was washed extensively. Next, alkaline phosphatase (AP)-coupled goat anti-human IgG diluted 1:1000 (Southern Biotech cat. #2040-04) was added 100 μl per well, and incubated for 1 hour at ambient temperature, followed by detection with AP conversion of colorimetric substrate consisting of p-nitrophenyl phosphate disodium salt (PNPP, Peirce cat. #37620). Absorbance was measured at 405 nm. Results were expressed as average OD₄₀₅ values±standard deviations (n=3). Background values resulting from non-specific sample binding to uncoated wells (binding buffer only) was subtracted from the values obtained from binding to H5 HA coated wells.

Example 2 Results for B Cells Reactive to H5 HA

Toll-Like Receptor (TLR) ligands and EBV concentration did not significantly improve EBV infectivity. Traggiai et al. (2004) reported that addition of at least one TLR ligand (CpG) to cultured memory B cells could enhance EBV infection efficiency. Since naïve B cells express several TLR (Bourke et al., 2003) it was reasonable to assess the effect of several TLR ligands on EBV infection of naïve B cells. Primary B cells were incubated overnight with either Pam3 (Pam₃Cys-Ser-(Lys)₄) (0.5 μg/mL), zymosan (1 μg/mL), Poly I:C (polyinosinic-polycytidylic acid) (25 μg/mL), LPS (lipopolysaccharide) (5 μg/mL), Imiquimod (1 μg/mL), CpG (10 μg/mL), or no ligand. These are synthetic proteins that mimic common pathogenic antigens. Each of these activates different innate immune pathways in B-cells. Lipopeptide Pam3 (Hamilton-Williams et al., 2005) binds TLR 2 and 1, zymosan (a yeast cell wall component prepared from Saccharomyces cerevisiae) binds TLR 2 and 6, Poly I:C (a viral double stranded DNA mimic) binds TLR 3, LPS (a microbial cell wall component) binds TLR 4 (Hamilton-Williams et al., 2005), Imiquimod (a small-molecule compound in the imidazoquinoline family, which displays both antiviral and antitumor effects) binds TLR 7, and hypomethylated CpG DNA binds TLR 9 (Hamilton-Williams et al., 2005). The inventors chose these TLR ligands because they bind to a wide range of TLR and would give a good range of activities. Following overnight incubation, the cells were infected with two different preparations of unconcentrated B95-8 EBV (prep 1, prep 2). As shown in FIG. 1A, Imiquimod, Pam3 and CpG addition improved infection efficiency to nearly 1.5% in some cases, but the overall infectivity was very low. In addition, variation between viral stock preparations significantly affected viral infectivity (FIG. 1A).

Since the addition of TLR ligands did not increase infection efficiency sufficiently for the inventors needs, viral concentration was pursued because of success with increasing retrovirus infection (Kanbe & Zhang, 2004). Viral concentration has been used to achieve higher virus titer and greater infectivity; concentration can be achieved through several techniques. For these studies, the inventors used ultrafiltration centrifugation to concentrate the EBV 10-fold. Concentrated or unconcentrated EBV was applied to primary B cells, and infectivity was determined using phase microscopy to assess lymphoblast formation. These findings indicated that concentration of EBV improved infection efficiency to nearly 5%, as compared to unconcentrated virus from the same preparation which reached only 1% infectivity (FIG. 1B). While viral concentration significantly increased infectivity, it was still not sufficient to immortalize a large portion of the naïve B cell repertoire.

The combination of viral concentration and “spinfection” increased EBV infectivity. “Spinfection” or “spinoculation” has been reported to enhance the infectivity of other enveloped viruses such as HIV (Audige et al., 2006; O'Doherty et al., 2000). This technique involves combining cells and viral stock, then centrifuging this combination at low speeds for one hour. To evaluate concentration and “spinfection” techniques, the adherent cell line Q293A was infected with recombinant EBfaV-GFP virus, in which EBV latent gene LMP2a was replaced with the enhanced green fluorescent protein EGFP gene (Speck et al, 1999). Q293A cells were inoculated for 24 hours with concentrated or unconcentrated preparations of EBfaV-GFP virus stocks, or were “spinfected” for 1 hour at 900 G with concentrated virus. FIG. 2A demonstrated the low infection efficiency of unconcentrated virus. A marked increase of infectivity over unconcentrated virus was observed with a 10-fold concentration of EBfaV-GFP (FIG. 2B). In FIG. 2C, Q293A cells were “spinfected” with concentrated virus; the combination increased infection efficiency over inoculation with either unconcentrated or concentrated virus (FIGS. 2A-C).

While “spinfection” and EBV concentration increased infection efficiency of an established cell line, these techniques still needed to be evaluated on primary human B cells, and infection efficiency needed to be quantified. Primary tonsil B cells were “spinfected” with concentrated non-fluorescent B95-8 EBV or with fluorescent EBfaV-GFP and analyzed for EGFP expression 24 hours post-infection. Visual inspection of the infection efficiency using a fluorescent microscope revealed that the combination of virus concentration and “spinfection” was effective on tonsil B cells (FIG. 3A). The infection efficiency was quantified by flow cytometry for EGFP expression 24 hours after infection. The combination of “spinfection” and concentration significantly increased EBV infection of primary B cells, such that 45% of EBfaV-GFP infected cells had higher fluorescence than B95-8 infected cells, with a mean fluorescence intensity (MFI) value of 61.9 compared with 15.1 (FIG. 3B). A shift of the entire peak in FIG. 3B indicated that nearly 100% of B cells were infected with EBfaV-GFP using this method, which was a great improvement over inoculation with unconcentrated virus and would be sufficient for immortalizing a large portion of the tonsil B cell repertoire.

Overall, these results on the optimization of EBV infection of B cells indicated that TLR ligand stimulation and viral concentration did not increase infection efficiency adequately for the inventors' needs. However, the combination of viral concentration and “spinfection” dramatically increased infection of primary B cells.

T cell derived cytokines had varying effects on IgM and IgG secretion from different samples. Naïve B cells are activated through interactions between the B cell receptor (BCR) and specific antigen; activation is helped by co-stimulatory signals from T cells. B cell differentiation in vivo is dependent upon T cell help. Therefore, the inventors postulated that if one could supply both T cell derived growth and differentiation factors, while cross-linking the BCR to mimic antigen, EBV immortalized LCLs could be forced to differentiate in vitro.

To test this postulate, the inventors examined the effect that different cytokine and/or signaling molecule combinations had on differentiation, specifically, as determined by IgG secretion. To examine the effects that these agents had on IgM and IgG secretion, primary tonsil B cells were infected with B95-8 EBV, treated with cytokines or other agents listed in Table 4 or the combinations of these as outlined in FIG. 4, and one week later, culture supernatant was analyzed for IgM or IgG by ELISA. FIG. 4 shows the secretion patterns of IgM and IgG in three different samples, one week after infection and treatment. IgM was primarily secreted at higher levels than IgG by all of the samples after most cytokine treatments (FIG. 4). Specifically, BAFF treatment or the combination of BAFF and CD40L increased IgM secretion over untreated cells (FIG. 4), while B cells treated with cytokine combinations containing anti-IgM (Fab′)₂ in general decreased total immunoglobulin secretion after one week, when compared to untreated controls (FIG. 4). Since similar patterns of immunoglobulin secretion were obtained from three different donor samples, the signaling agents had reproducible effects. Also, since the majority of immunoglobulin secretion was IgM, this indicated that a large portion of the tonsil B cells had not undergone immunoglobulin isotype class switching or affinity maturation.

TABLE 4 Cytokines and Factors For Ig Class Switching Cocktail Working Name Function Concentration Anti-IgM Goat anti-human IgM F(ab′)₂; cross-links IgM, thus 1.62 ng/ml F(ab′)₂ mimicking specific antigen binding; activates differentiation and Ig switching pathways IL-4 Cytokine produced by activated T cells and other 0.2 ng/ml immune cells; participates in several B-cell activation processes, including enhanced secretion and surface expression of IgE an IgG IL-5 Cytokine secreted by Th2 cells; acts as a growth and 0.22 ng/ml differentiation factor for both B-cells and eosinophils; promotes production of Ig IL-6 Cytokine plays a role in B-cell growth and 0.1 ng/ml differentiation of multiple stages including the final differentiation of B-cells into Ig-secreting plasma cells IL-9 Cytokine secreted by Th2 cells; stimulates cell 2 ng/ml proliferation and growth and prevents apoptosis IL-10 Cytokine produced primarily by monocytes and 2.4 ng/ml lymphocytes; enhances B-cell survival, proliferation and antibody production IL-13 Cytokine produced by activated Th2 cells; involved 10 ng/ml in B-cell maturation and differentiation; up- regulates CD23 and MHC II class II expression and promotes IgE isotype switching IFNα Cytokine produced by stimulated T lymphocytes 12.5 ng/ml and many other cell types; enhances MHC I and II expression; activates a subset of antiviral genes BAFF B lymphocyte activating factor; expressed by 10 ng/ml monocytes, macrophages and dendritic cells; plays a role in B lymphocyte development, selection and homeostasis CD40L Ligand for CD40; CD40 signaling induces B-cell 5 ng/ml differentiation and Ig hypermutation

Anti-IgM(Fab′)₂, CD40L and/or cytokines induced immunoglobulin isotype class switching after several weeks in culture. Tonsil B cells were treated with cytokines and signaling agents for three weeks; culture supernatant was analyzed by ELISA after each week for up to 10 weeks. The tonsil B cells from two of the donor samples represented in FIG. 4 were treated with a limited panel of signaling agent combinations for three weeks. While these samples initially secreted primarily IgM after one week (FIG. 4), the expression pattern of IgM and IgG changed with time in vitro. Starting as soon as 10 days after culture, immunoglobulin isotype class switching occurred after treatment with particular combinations of cytokines. As can be seen in FIG. 5, for cells cultured for more than 8 weeks, the immunoglobulin expression pattern was clearly different (FIGS. 5A and 5B). Continued cytokine treatments with CD40L alone, or anti-IgM(Fab′)₂ in combination with IL-6, resulted in high levels of IgG secretion (FIG. 5A). This increase in IgG was accompanied by a drop in IgM secretion (FIG. 5A). In contrast, B cells treated with anti-IgM (Fab′)₂ and IL-4 secreted higher levels of IgM than IgG (FIGS. 5A and 5B). FIG. 5B showed that cells cultured with CD40L, anti-IgM(Fab′)₂ and BAFF also resulted in preferential IgG secretion. In all cases, the B cells continued to secrete immunoglobulin at high levels for many weeks. These results suggested that the LCLs had undergone immunoglobulin isotype class switching from IgM to IgG after treatment with the signaling agents.

Treatment with signaling agents induced differentiation of EBV immortalized B cells to early plasma B cell stage. FIGS. 5A and 5B demonstrated that EBV immortalized cells treated with anti-IgM (Fab′)₂ and IL-6, soluble CD40L alone, or anti-IgM (Fab′)₂, BAFF and soluble CD40L, preferentially increased IgG secretion, while EBV immortalized cells treated with anti-IgM (Fab′)₂ and IL-4, or cultured in the absence of cytokines and signaling agents with media only, mainly secreted IgM. Immortalized cells secreted high amounts of immunoglobulin for more than 20 weeks (data not shown). These observations, when taken together, indicated B cell differentiation had occurred. In order to investigate whether immortalized B cells differentiated into plasma-like cells in vitro, EBV immortalized B cells treated with anti-IgM(Fab′)₂ and IL-4 or IL-6, and secreting primarily IgM or IgG, respectively, were stained for common B cell surface markers (see Table 5 for description) and compared with primary tonsil B cells prior to immortalization. FIG. 6A showed that uninfected primary tonsil B cells (top panel) were mostly naïve or had not undergone immunoglobulin isotype class switching. Primary tonsil B cells stained positive for the pantropic B cell surface markers CD19 and CD20, and a large portion of the cells stained positive for surface immunoglobulin IgD, which is a marker of naïve B cells and mature B cells that have not undergone immunoglobulin isotype class switching or somatic hypermutation. In addition, the primary cells had low level expression of activation markers CD27 and CD30 (FIG. 6A). In contrast, immortalized cells that secreted primarily IgM or IgG (FIG. 6B, bottom panel) phenotypically resembled early plasma cells; as would be expected, both populations were positive for the pan B cell marker CD19, but they had decreased expression of CD20, which is commonly lost on plasma B-cells, and IgD, which is a marker of naïve and early stage mature B cells, while they had increased expression of the activation markers CD30 and CD27 (FIG. 6B). Immortalized B cells secreting primarily IgG or IgM differed only in the expression of CD38, which is a terminal differentiation marker that was up-regulated on the IgG secreting cells (FIG. 6B). These results confirmed that the immortalized cells treated with signaling agents had indeed differentiated in vitro.

TABLE 5 CELL DETERMINANTS USED TO CHARACTERIZE B-CELL POPULATIONS BY FLOW CYTOMETRY Marker Function Expression CD19 Assembles with the BCR and modulates Pantropic B-cell the threshold for antigen-specific marker receptor-dependent stimulation CD20 B cell surface molecule with a role in B Present on all cell differentiation and calcium mature B conductance lymphocytes, except plasma cells CD27 Member of the NGF/TNF receptor Marker for human superfamily. Soluble CD27 is produced somatically mutated by terminally differentiated cells, e.g. cells. Found on both plasma B cells B and T lymphocytes upon cell activation CD30 Transmembrane cytokine receptor Present on B belonging to the TNF superfamily, has a lymphocytes after role in regulating the function, activation differentiation an/or proliferation of normal lymphoid cells CD38 Functions in cell adhesion, signal Appears on bone transduction and calcium signaling; co- marrow precursor receptor for superantigens of viral or cells, is also bacterial origin present on terminally differentiated B cells IgD Immunoglobulin molecule with Present on mature unknown function naïve B lymphocytes

Summary: To date, Epstein-Barr virus infection of primary B cells with recombinant EGFP expressing virus has been optimized to achieve an overnight population of fluorescent cells with significantly increased mean fluorescent activity (MFI), for example, 61.9 compared with a background MFI of 15.1, through viral concentration using centrifugal ultrafiltration and “spinfection” technique. Combinations of signaling agents (CD40L alone or in combination with anti-IgM (Fab′)₂ and BAFF; or anti-IgM (Fab′)₂ in combination with IL-6, with or without IL4) were identified that consistently increased B-cell activation and differentiation, resulting in preferential secretion of IgG. Other combinations of cytokines inconsistently induced IgG secretion, e.g., IL-9 and IL-13. Flow cytometric staining with antibodies specific for different B cell surface markers, indicated that EBV immortalized B LCLs that had been induced to differentiate in vitro, resembled plasma B cells, and not the early stage primary tonsil B cells from which they derived.

H5N1 hemagglutinin (HA) specific antibodies were found in sera of healthy humans. The creation of plasma cells in vitro, suggested that the process might be exploited for the creation of human monoclonal antibodies specific for targets of interest, like avian influenza. While most people have not been exposed to avian influenza, they have been exposed to other closely related flu strains. Therefore it is reasonable to assume that healthy individuals may have memory B cells that were stimulated by human influenza viruses and which cross-react with the H5 HA protein of avian influenza. To confirm if H5 HA reactive IgG antibodies were present in the blood of healthy individuals, serum was collected from five healthy volunteers that had never been exposed to H5N1 avian influenza (HS 1-5), and then assayed by ELISA for antibodies that bind to commercially obtained recombinant H5 HA. To detect these antibodies in the serum, an ELISA using recombinant H5 HA was created. H5 HA specific binding was calculated by subtracting out background from total binding (described in methods). Four donors (HS 1, 2, 3, 5) had varying amounts of H5 HA-specific IgG in the serum (FIG. 7) with donors HS 3 and 5 having the highest reactivity. In contrast, donor HS 4 had lower reactivity than the negative controls, which consisted of the humanized monoclonal antibody rituximab, specific for CD20 antigen (Rituxan^(R)), or purified total human IgG, indicating that this volunteer lacked H5 HA cross-reactive IgG antibodies (FIG. 7). The detection of H5 HA-specific IgG in the serum of healthy volunteers indicated that the H5 HA reactive IgG antibodies could be detected by ELISA screening. However, the inventors could not use the ELISA to detect IgM antibody binding because background binding was too high to yield meaningful results (data not shown). These results bolstered the hypothesis that IgG antibodies specific for H5 hemagglutinin of avian influenza could be created by exploiting the B cell differentiation pathway in EBV immortalized cells, since they indicated that healthy humans never exposed to H5N1, have the ability to make an antibody response against the virus.

Immortalized B cell repertoires from PBMC secreted IgG antibodies specific for H5 HA. The ELISA results suggested that B cell clones of a given specificity could be isolated from individuals that have not been exposed to H5N1 avian influenza. To test the immortalization and differentiation techniques, PBMC were extracted from Volunteer 5 (HS5=V5). B cells were cultured using two different cytokine/signaling agent combinations: (1) anti-IgM (Fab′)₂, IL-4 and IL-6 (see PBMC A1 results); (2) anti-IgM (Fab′)₂, CD40L and BAFF (see PBMC A2 results).

PBMC A1: B cells were isolated from PBMC of volunteer HS 5 and immortalized with EBV as described in methods and as summarized in Table 6. Cells were treated with anti-IgM(Fab′)₂, IL-4 and IL-6 to induce B cell differentiation and immunoglobulin production, and were then plated in three 96-well plates. After one week, culture supernatants from all wells on each plate were collected and pooled; there was little or no H5 HA-specific IgG binding detected in the pooled supernatant samples from any of the three plates, compared with the human serum control (FIG. 8). However, after two weeks of treatment, H5 HA-specific IgG was detected in pooled culture supernatants from all three plates of B cells (FIG. 8, Plate1, Plate 2 and Plate 3). To determine the location of the reactive B cell clones secreting the H5 HA reactive IgG, all wells in each row on reactive plates were pooled and assayed. Several rows from each of the three plates contained H5 HA-reactive B cells (plate 1, row E; plate 2, rows C, D and E; and plate 3, row D) (FIG. 9). FIG. 10 indicated that the most reactive B cells were located on plate 2, in pooled supernatant from adjacent wells 11 and 12 on row D. With further analysis of the supernatants, the reactive B cells were found to be on plate 2, in row D, well 11 (FIG. 11); these cells were secreting H5 HA-reactive IgG at a level similar to the positive serum control (FIG. 11). This well was subcloned; however, the H5 HA-reactive B cells died before they could be isolated after 12 weeks of culture. A summary of the clonal isolation scheme and findings are summarized in FIG. 12 and Table 6.

TABLE 6 Summary of data on screening and production of immortalized human B cells secreting antibodies reactive with H5 HA # of Treatment for # of sub- # of inducing B Date B cells # of cloned possible cell H5 HA Sample received (×107) plates wells clones differentiation specific IgG Status PBMC Jan. 16, 2007 0.2 3 1 0 Anti-IgM Positive Subcloned 1 well: A1 (Fab′)2, IL-4, originally PA1-2D11 IL6 lost reactivity PBMC B Feb. 16, 2007 0.2 3 0 0 Anti-IgM Negative Screening (Fab′)2, IL-4, discontinued: IL6 negative at week 3 PBMC Mar. 14, 2007 0.6 6 3 0 Anti-IgM Positive Subcloned 3 wells; A2 (Fab′)2, originally lost reactivity CD40L, BAFF PBMC C Sep. 22, 2007 3 10 1 1 Anti-IgM Positive Subcloned 1 well (PC- (Fab′)2, originally 9F9) CD40L, BAFF lost reactivity PBMC Jan. 28, 2008 4 10 2 2 Anti-IgM Positive Subcloned 2 wells: A3 (Fab′)2, originally (PA3-4F5, PA3-3F2) CD40L, BAFF lost reactivity TNSL A Jan. 22, 2007 20 10 2 0 Anti-IgM Positive Screening (Fab′)2, IL-4, lost discontinued: IL6 week 3 fungal contamination TNSL B Mar. 26, 2007 20 10 0 0 Anti-IgM Negative Screening (Fab′)2, discontinued: CD40L, BAFF negative at week 4 TNSL C Apr. 16, 2007 22 10 0 0 Anti-IgM Negative Screening (Fab′)2, discontinued: CD40L, BAFF negative at week 3 TNSL D Apr. 23, 2007 15 10 1 0 Anti-IgM Positive Subcloned 1 well; (Fab′)2, originally lost reactivity CD40L, BAFF TNSL E May 14, 2007 4 4 1 2 Anti-IgM Positive Subcloned 1 well, 2 (Fab′)2, clones isolated: CD40L, BAFF (TE-3A10-E3A5, TE- 3A10-C7F6) TNSL F Sep. 24, 20 10 0 0 Anti-IgM Negative Screening 2007 (Fab′)2, discontinued: CD40L, BAFF negative at week 3 TNSL G Nov. 19, 13 10 0 0 Anti-IgM Negative Screening 2007 (Fab′)2, discontinued: CD40L, BAFF negative at week 3 TNSL H Nov. 19, 12.5 10 0 0 Anti-IgM Negative Screening 2007 (Fab′)2, discontinued: CD40L, BAFF negative at week 3 TNSL I Dec. 10, 10 10 0 0 Anti-IgM Negative Screening 2007 (Fab′)2, discontinued: CD40L, BAFF negative at week 4 TNSL J Jan. 07, 11 10 2 2 Anti-IgM Positive Subcloned 2 wells: 2008 (Fab′)2, (TJ-1G6, TJ-1C8); CD40L, BAFF both at tertiary subcloning stage TNSL K Jan. 14, 13.5 10 0 0 Anti-IgM Negative Screening 2008 (Fab′)2, discontinued: CD40L, BAFF negative at week 3 TNSL L Feb. 01, 8 10 0 0 Anti-IgM Negative Screening 2008 (Fab′)2, discontinued: CD40L, BAFF negative at week 3 TNSL M Feb. 05, 17 10 2 2 Anti-IgM Positive Subcloned 2 wells: 2008 (Fab′)2, originally (TM-7C2, TM-7F8) CD40L, BAFF reactivity lost TNSL N Feb. 05, 5 10 1 1 Anti-IgM Positive Subcloned 1 well: 2008 (Fab′)2, (TN-6G7); isolated CD40L, BAFF clone TN-6G7-7F8- 2G7 TNSL O Feb. 06, 23 10 0 0 Anti-IgM Negative Screening 2008 (Fab′)2, discontinued: CD40L, BAFF negative at week 2 TNSL P Mar. 11, 27 10 1 1 Anti-IgM Positive Subcloned 1 well: 2008 (Fab′)2, (TP-2C2) secondary CD40L, BAFF subcloning stage TNSL Q Mar. 18, 18.8 10 0 0 Anti-IgM Negative Screening 2008 (Fab′)2, discontinued: CD40L, BAFF negative at week 2 TNSL R Mar. 31, 2008 21 10 1 1 Anti-IgM Positive Subcloned 1 well; (Fab′)2, originally (TR-8E9) CD40L, BAFF lost reactivity TNSL S Mar. 31, 2008 17 10 2 2 Anti-IgM Positive Subcloned 2 wells (Fab′)2, originally (TS-8G1, TS-1A8); CD40L, BAFF lost reactivity TNSL V May 2, 2008 8 10 0 0 Anti-IgM Negative Bead assay used; (Fab′)2, Screening CD40L, BAFF discontinued: negative at week 3 TNSL W May 14, 2008 14 10 0 0 Anti-IgM Negative Screening (Fab′)2, discontinued: CD40L, BAFF negative at week 2 TNSL X May 19, 2008 11 10 0 0 Anti-IgM Negative Screening (Fab′)2, discontinued: CD40L, BAFF negative at week 2 TNSL Z Jun. 2, 2008 12.5 10 3 3 Anti-IgM Positive Subcloned 3 wells: (Fab′)2, (TZ-4F12, TZ-10G1, CD40L, BAFF TZ-10G9) TNSL α Jun. 6, 2008 7 10 1 1 Anti-IgM Positive Subcloned 1 well: (Fab′)2, (Ta-6G8) CD40L, BAFF TNSL β Jun. 11, 2008 11 10 0 0 Anti-IgM Negative Screening (Fab′)2, discontinued: CD40L, BAFF negative at week 2 TNSL γ Jun. 18, 2008 12 10 0 0 Anti-IgM Negative Screening (Fab′)2, discontinued: CD40L, BAFF negative at week 2

PBMC A2: B cells were isolated a second time from PBMC of Volunteer HS 5 and infected with EBV as described in the methods and as summarized in Table 6. Cells were then induced to differentiate by treatment with anti-IgM (Fab′)₂, CD40L, and BAFF as described in the methods. (This combination of agents improved levels of IgG antibody production over the combination used on PBMC A1 and B.) Culture supernatants from all wells on each of six 96-well plates were collected weekly after infection, pooled and assayed for H5 HA reactive IgG antibodies. After 4 weeks, three wells on different plates (Plate 4 G8, Plate 5 E1 and Plate 6 C2) contained H5 HA reactive IgG. The three reactive wells were subcloned, and possible clones were subsequently identified from two of the wells as outlined in FIG. 13, and summarized in Table 6. H5 HA-reactive B cells died after 10 weeks in culture prior to their isolation.

PBMC B: B cells were isolated from peripheral blood of Volunteer 6 and immortalized with EBV as described in the methods, and as summarized in Table 6. The immortalized cells were treated with anti-IgM (Fab′)₂, IL-4 and IL-6 and plated into three 96-well plates. After three weeks of cytokine treatments no H5 HA-specific IgG antibodies were detected in the supernatant or serum of Volunteer 6 (FIG. 14). Analysis of this sample was discontinued due to the repeated lack of H5 HA reactivity in either the serum or the supernatant of immortalized cells.

Summary: Peripheral blood derived B cells from two volunteers were isolated and immortalized with EBV, then induced to differentiate with either anti-IgM (Fab′)₂, IL-4 and IL-6; or anti-IgM (Fab′)₂, CD40L, and BAFF. B cells that secrete H5 HA reactive IgG antibodies were isolated from one of the volunteers, on two separate occasions (PBMC A1 and A2), and induced to differentiate using either method. The Different cytokine combinations were tested with the aim of optimizing the efficiency of inducing immunoglobulin isotype class switching, in order to obtain more H5 HA reactive IgG secreting B cell cells in these samples. While this change yielded more reactive cells from PBMC A2 repertoire than from PBMC A1 repertoire, the difference was not significant. The samples were isolated from the same volunteer a little over a month apart. In contrast, B cells isolated from Volunteer 6 did not yield any reactive clones. These results are summarized in Table 6.

Immortalized B cell repertoires from tonsils secreted IgG antibodies specific for H5 HA. While immortalized B cells that produced H5 HA-reactive IgG were successfully isolated from peripheral blood (PBMC), in order to prove that they were inducing differentiation of naïve B cells, a naïve population of cells for creation of the repertoire was obtained from tonsil B cells from otherwise healthy children undergoing tonsillectomy for medical reasons. As demonstrated in FIG. 6A, tonsil B cells are mainly naïve or have not undergone immunoglobulin isotype class switching. The inventors repeated the experiments performed on the peripheral blood samples on 26 tonsil samples (summarized in Table 6). The treatment for inducing differentiation was changed from anti-IgM (Fab′)₂, IL-4 and IL-6 after the first tonsil (TNSL A) to anti-IgM (Fab′)₂, CD40L and BAFF for all of the rest (TNSL B-E), because the second combination selectively increased IgG secretion (data not shown). Representative results from several of the tonsil repertoires are shown in FIG. 15-32.

TNSL A: B cells were isolated from tonsil, immortalized with EBV, treated with anti-IgM (Fab′)₂, IL-4 and IL-6, and then cultured in ten 96-well plates, as described in the methods and as summarized in Table 6. After one week, no H5 HA reactive IgG was detected. However, after two weeks of cytokine treatments, H5 HA binding activity was detected on two (plates 6 and 9) out of ten plates (FIG. 15). After three weeks, two rows (C and F on plate 9) were identified as having cross-reactive IgG; unfortunately, this sample was lost due to fungal contamination and analysis was discontinued (FIG. 15). Despite the loss, this sample demonstrated that obtaining IgG reactivity to the antigen of interest was possible from tonsil B cells.

TNSL B: B cells were isolated from tonsil, immortalized with EBV, treated with anti-IgM (Fab′)₂, CD40L and BAFF, to increase IgG antibody production and plated in ten 96-well plates, as described in methods and as summarized in Table 6. Low levels of H5 HA reactive IgG was detected on Plate 3 row D after two weeks of analysis, but no reactivity was recovered subsequently; therefore, sample analysis was discontinued (FIG. 16).

TNSL C: B cells were isolated from tonsil, immortalized with EBV, stimulated with anti-IgM (Fab′)₂, CD40L and BAFF and plated in ten 96-well plates, as described in the methods and as summarized in Table 6. After the first week, H5 HA reactive IgG was detected on plates 7, 8, 9 and 10 (FIG. 17) at very low levels. However, after two weeks no H5 HA reactive IgG antibodies were detected on any of the plates and no reactivity was subsequently recovered. Therefore, sample analysis was discontinued after four weeks (FIG. 17).

TNSL D: B cells were isolated from tonsil, immortalized with EBV, stimulated with anti-IgM (Fab′)₂, CD40L and BAFF and plated in ten 96-well plates, as described in the methods and as summarized in Table 6. After one week, there was no detectable H5 HA reactive IgG in the culture supernatant (FIG. 18). However, after 2 weeks, H5 HA reactive IgG was identified on plates 1, 8, 9 and 10 (FIG. 19). Plate 10 exhibited robust H5 HA reactivity, similar to human serum from volunteer HS 5; therefore, culture supernatants from individual wells were analyzed immediately. The other plates lost binding strength after the second week and were not pursued for subcloning. The reactive B cells were found on plate 10, row G, in pooled samples from adjacent wells 3 and 4, which exhibited binding levels similar to human serum controls (FIG. 20). The reactive well was identified as G4 (FIG. 21); however, reactivity was reduced, indicating that the cells producing the antibody might have begun to die. B cells from this well were subsequently subcloned, but as was shown in FIG. 29, the cells producing H5 HA-reactive IgG did not survive, and could not be isolated. The isolation scheme is summarized in FIG. 22.

TNSL E: B cells were isolated from tonsil, immortalized with EBV, stimulated with anti-IgM (Fab′)₂, CD40L and BAFF and plated in four 96-well plates, as described in the methods and as summarized in Table 6. After one week, plates 1 and 3 were weakly reactive to H5 HA (FIG. 23). After two weeks, plate 1, rows B and E and Plate 3, row A were identified as containing B cells that secreted IgG reactive with H5 HA (FIG. 24). Analysis of culture supernatants from pooled adjacent wells determined that plate 1, row B wells 5 and 6, row E, wells 3 and 4, 11 and 12; and plate 3 row A, wells 9 and 10 contained IgG reactive with H5 HA (FIG. 25). Of these paired wells, plate 1 row E well 11 and plate 3, row A, well 10 contained H5 HA reactive IgG (FIG. 26). Plate 3 well A10 was subcloned because it had the strongest H5 HA binding. Reactivity was detected in wells containing only 1000 cells after five weeks (FIG. 27). The isolation scheme for the primary round of subcloning was summarized and outlined in FIG. 28. H5 HA reactivity was identified during the primary round of subcloning on a plate containing 1000 cells per well (FIG. 29). The reactive cells were identified in wells C7 and E3 (FIGS. 30A and 30B). Cells from these wells were subjected to two additional rounds of limiting dilution cloning, resulting in identification of two H5 HA-reactive clones, TE-3A10-E3A5 and TE-3A10-C7F6, (FIG. 30C), sometimes referred to as E3A5 and C7F6, respectively.

Characterization of TNSL-E derived H5 HA reactive clones, TE-3A10-C7F6 and TE-3A10-E3A5. To evaluate specificity of binding to H5 HA, the relative affinity for TE-3A10-C7F6 and TE-3A10-E3A5 (C7F6 and E3A5) binding to H5 HA compared with their affinities for H1 HA and H7 HA was studied. ELISA assays specific for H1 and H7 HA were developed. Culture supernatants from clones C7F6 and E3A5 were assayed for relative binding, in comparison with human sera from 5 healthy adult volunteers (FIG. 31). Most healthy adults would be expected to have an antibody response against H1 HA, because most human influenza virus infections are caused by H1 strain viruses, and H1 HA is a component of the yearly flu vaccine. As can be seen in FIG. 31, all volunteers had H1 HA reactive IgG in serum, but had much lower serum reactivity to H5 HA and H7 HA, as would be expected because H5 and H7 are avian influenza strains. In contrast, both clones C7F6 and E3A5 secreted IgG that bound to H5 HA with significantly more reactivity than bound to H1 or to H7 HA (FIG. 31), indicating that both C7F6 and E3A5 were relatively specific for H5 HA. Interestingly, the H5 HA reactive clones had some cross-reactivity to the human strain H1 HA, but had low level reactivity with the other avian H7 strain. Purified human IgG was used as control, and as can be seen in FIG. 31, H1 HA reactivity was also present in this sample, consistent with the strong reactivity with H1 HA found in all donors.

A dose response type experiment indicated that the C7F6 and E3A5 clones produced approximately 20-50 pg of IgG per cell per day. E3A5 and C7F6 cells were washed with DPBS and seeded into wells of a 96-well plate at 10,000, 5,000, 2,500 and 1,250 cells per well, in the same volume of culture media (200 μl per well). Culture supernatants were collected 72 hours later and evaluated for IgG and IgM levels. Calculation of the levels of IgG and IgM produced by the clones in each test sample was performed by comparing the experimental values with those derived from a standard curve, established by serially diluting purified IgG and IgM of known concentration. As can be seen in FIG. 32, both C7F6 and E3A5 cells produced only IgG in a dose-dependent manner. As expected, IgM was not produced (FIG. 32), (residual background levels of IgM seen at the highest cell number resulted from cross-reactivity of the goat anti-human IgM ELISA detection antibodies with human IgG). At the highest cell density (10,000 cells per 200 μl), the clones produced 4-5 micrograms per ml of media in 72 h. Combining the data from each sample at all cell densities, the average IgG production per cell per 24 hours was calculated. E3A5 cells produced on average 49±16 picograms of IgG per cell per 24 hours, while C7F6 cells produced 21±11 pg of IgG per cell per 24 hr (FIG. 32). Because E3A5 cells grew faster than C7F6 cells at lower cell density (data not shown), these differences might not be significant.

Next the IgG subtype(s) produced by the C7F6 and E3A5 isolates were identified. Human IgG has 4 subtypes, IgG₁, IgG₂, IgG₃ and IgG₄, with IgG₁ and IgG₄ being the most and least common, respectively. To identify the subtype of each clone, culture supernatants from both isolates were tested by ELISA, using as detection antibodies murine monoclonal antibodies that specifically recognized human IgG₁, IgG₂ and IgG₃, the three most common subtypes, each coupled to alkaline phosphatase (AP). As can be seen in (FIG. 33), both C7F6 and E3A5 secreted IgG₁. As positive control, AP-labeled polyclonal goat anti-human IgG was used, which binds all IgG subtypes better than the IgG1 specific monoclonal antibody, leading to higher OD₄₀₅ values (FIG. 33).

Analysis of the heavy and light chain variable region sequences of the H5 HA binding immunoglobulins produced by the TE-3A10-E3A5 and TE-3A10-C7F6 clones. Total RNA was extracted from approximately 10⁶ cells of each clone using RNEasy protocol (Qiagen, #74104) with QIAshredder columns (Qiagen, #79654). RNA was converted to cDNA with the High Capacity cDNA Reverse Transcription Kit according to manufacturer's instructions (Applied Biosystems, #4368813) and analyzed by PCR for light and heavy chain type content using a set of primers adapted from Welschof et al. (1995) (FIG. 34A). All forward primers incorporated an XbaI restriction site, while the reverse primers incorporated a SalI restriction site. PCR products were analyzed on 1% agarose gel (FIG. 34B), indicating that both E3A5 and C7F6 had λ1 light chain, and E3A5 had V_(H3) heavy chain, while C7F6 had V_(H1) heavy chain. Reactions that resulted in detectable product were scaled up using the proofreading Accuzyme™ Mix kit (Bioline, # BIO-25027). PCR products were gel-purified using QIAquick Gel Extraction Kit (Qiagen, #28704), and a portion of each was submitted for sequencing to the MUSC DNA Core Facility with the original forward and reverse PCR primers. The remainder of each product was digested with XbaI and SalI (New England Biolabs), and cloned into XbaI/SalI digested pSP73 plasmid (Promega, # P2221) for subsequent subcloning into mammalian expression vectors. Forward and reverse DNA sequences were aligned using Vector NTI (Invitrogen) ALIGN function, and combined corrected sequences were generated. These were analyzed using VBASE2 online software (Retter et al., 2005). Results of this analysis are shown in FIG. 35A-35E. Sequence numbering and motif alignments were performed according to Kabat standards (Johnson and Wu, 2000). E3A5 (SEQ ID NOS:16 and 17) had V_(L) gene segment IGLV063 and J_(L) segment IGLJ3*02, with homology to germline sequences at 99% and 100%, respectively (FIG. 35A). C7F6 (SEQ ID NOS:19 and 20) had V_(L) gene segment IGLV067 and J_(L) segment IGLJ1*01, with homology to germline sequences at 99% and 100%, respectively (FIG. 35B). E3A5 (SEQ ID NOS:22 and 23) had V_(H) gene segment IGHV157, D_(H) segment IGHD4-17*1, and J_(H) segment IGHJ3*02, with homology to germline sequences at 90%, 93% and 96%, respectively (FIG. 35C). C7F6 (SEQ ID NOS:25 and 26) had V_(H) gene segment IGHV220, D_(H) segment IGHD2-2*03, and J_(H) segment IGHJ6*02, with homology to germline sequences at 90%, 93% and 96%, respectively (FIG. 35D). The light and heavy chain complementarity determining regions for both C7F6 and E3A5 are depicted in FIG. 35E (SEQ ID NOS:28, 29, 30, and 31).

Example 3 Materials & Methods for Producing Human B-Cells Secreting Monoclonal Antibodies Reactive with SEB, SEC-2, PLGF, and Ricin B Chain

Creation of immortalized tonsil repertoires. Generation of concentrated EBV stocks and preparation of B cells from tonsil tissue have been described in Examples 1 and 2. No changes have been made to these methods. For induction of differentiation of EBV immortalized B cells, the inventors used complete RPMI medium (Gibco) supplemented with 10% FBS (Hyclone) containing soluble CD40 ligand (5 ng/ml), BAFF (10 ng/ml), and goat anti-human IgM F(ab′)2 (1.62 ng/ml), as previously described.

Sample collection for ELISA analysis. Collection and screening of sample culture supernatants for antigen reactivity by ELISA have been modified as follows. Culture supernatants were collected into corresponding wells on a 96-well plate on day 10-14 post-transduction at 100 μl from each well, and aliquots were pooled (30 μl of supernatant from all wells on each plate) and screened by the specific ELISA for antigen reactivity. The culture supernatant was replaced with 100 μl fresh RPMI medium containing CD40L, BAFF and anti-human IgM(Fab′)2. If antigen reactivity was detected in pooled wells, each of the individual wells contributing to the pool was split into 5 new wells to preserve the viability of the culture while the identity of the positive well was confirmed by additional ELISA experiments. Once individual wells containing specific antigen reactive IgG had been identified in tonsil repertoires, using the rapid screening strategy, cells from that well were counted, and 50-80% of them were subcloned into 96-well plates (˜500-1000 cells per well, depending upon the count), while the remainder were frozen. After 7 to 10 days, supernatants were collected as outlined above and rapid screening analysis was repeated. This was followed by 2 additional rounds of limiting dilution subcloning and screening. Clonality was assumed when at the lowest dilution, clones were obtained in fewer than 30% of wells on the 96-well plate, and all clones on the plate were producing specific antigen reactive IgG.

SEB ELISA

Binding of test antigen to assay plate. The day before, add to 1× binding buffer (20 mM Tris-Cl pH 8.5) the SEB antigen (BT202red and biotinylated BT202 B, Toxin Technologies, Inc.) at 5 ug/mL. The amount of buffer to use is 5 mL per 96-well plate at 50 uL buffer/well. Note: SEB antigen kept in locked 80° C. freezer in SEB/SEC2 box. Each aliquot of 0.5 μg/μL SEB is individually labeled. Use aliquots in increasing order. Upon thawing and usage of an aliquot, record usage in the IBC notebook with the SEB toxin log. Using a multichannel pipettor, add 50 uL/well of the antigen-binding buffer mix to the test wells of a non-sterile, flat-bottomed 96-well plate (use CoStar EIA/RIA plate, no lid 96-well Easy Wash, prod #3369). For the control background wells, add 504 μL of 1× binding buffer (without antigen). Cover plate(s) with adhesive plate film and place at 4° C. overnight.

ELISA assay. Remove from the 20° C. freezer any supernatant samples needing for the assay and leave at room temperature to thaw. Prepare the plate washer (Wellwash 4 Mk2) as follows: Insert control card into right side of machine and turn machine on. Make sure parameters on the card are set as follows: Dials: Soak×0.5 min=0, Pause=0, Washes=3, Volume×504=4; Toggles: single, 12way, plate, stepoff, wash HI, dry, F1 off, F2 off, F dry. Empty waste reservoir if waste present. Replace dH₂O reservoir with 1×TBST reservoir. Make certain at least 500 mL/plate of TBST is in reservoir before starting. Press the <PRIME> button to flush the dH₂O from the system. With the “Wash Plate” in place, wash system by pressing <4> row button then <START> button. Plate washer should wash the first half of the plate 3 times then aspirate the plate leaving it dry.

Blocking. Remove adhesive plate film from plate to be washed and place on washer. Wash plate 3 times (press <8> then <START>). After washing, shake out any remaining TBST from plate with a sharp swing (do this after each wash from here on). Pipet 100 μL of blocking solution into each well using multichannel pipetter. Cover plate with adhesive plate film and leave at room temperature 1 hour.

Sample binding. If using samples of supernatant from a 96-well plate, briefly spin thawed sample plate in centrifuge at 2K rpm/2 mins/RT. Dilute any supernatant samples as needed. Use blocking solution to dilute so that 100 uL of diluted sample can be added per well. For duplicate assays with background controls, at least 400 uL of diluted sample will be needed. Wash blocked plate 3 times. Pipette samples onto plate according to plate diagram using 100 uL of sample/well. If needed, add (+) and (−) controls on plate (ex. 1:5000 dilution of mouse α-SEB monoclonal antibody in blocking buffer for SEB assay). Blank wells should have 100 uL of blocking solution added. Cover plate with adhesive plate film and place on plate shaker set for 1 hour at 450 rpm. To shake multiple plates, wrap a narrow strip of parafilm around plate stack before loading.

2° antibody binding. Make secondary antibody dilution. Use blocking solution and the appropriate antibody at the appropriate dilution. 100 μL is needed per well so 10 mL will be needed per plate. [For α-human IgG 2° Ab, use goat α-human IgG antibody at a dilution of 1:10,000 (1 μL 2° Ab/10 mL blocking solution). For the positive control mouse α-SEB monoclonal antibody, use 1:10,000 dilution of goat anti-mouse IgG-AP 2° Ab]. Post sample binding, remove from shaker and remove adhesive films. Change wash dial on control card from 3 to 4 and wash plate 4 times. Pipet 100 uL of secondary antibody into each well. Seal plate with new adhesive film and put on plate shaker for 1 hour at 450 rpm.

Substrate addition. 5 minutes before 2° Ab binding is completed, prepare reactant. For 1 plate, mix 2 mL of 5× substrate buffer with 8 mL diH2O and 2 reactant tablets in a 15 mL culture tube. Mix by inverting until tablets are fully dissolved. Remove plate from mixer and remove adhesive films. All procedures to be conducted in the fume hood to contain toxin. All waste products and consumables to be disposed of in biohazardous waste containers and autoclaved. Liquid waste to be treated with bleach at 10% prior to disposal. Use appropriate protective gear (gloves and safety goggles) during assay. Refer to SEB-specific IBC regulations prior to usage. Time to completion: Plate coating (the day before assay) 30 minutes ELISA assay 4-8 hours plus development time (30 min-24 h)

SEC2 ELISA

Binding of test antigen to assay plate. The day before, add to 1× binding buffer (20 mM Tris-Cl pH 8.5) the SEC-2 antigen at 5 μg/mL. The amount of buffer to use is 5 mL per 96-well plate at 50 μL buffer/well. Note: SEC-2 antigen kept in locked 80° C. freezer in SEB/SEC2 box. Each aliquot of 0.5 ug/uL SEC-2 is individually labeled. Use aliquots in increasing order. Upon thawing and usage of an aliquot, record usage in the IBC notebook with the SEC-2 toxin log. Using a multichannel pipettor, add 50 μL/well of the antigen-binding buffer mix to the test wells of a non-sterile, flat-bottomed 96-well plate (use CoStar EIA/RIA plate, no lid 96-well Easy Wash, prod #3369). For the control background wells, add 50 μL of 1× binding buffer (without antigen). Cover plate(s) with adhesive plate film and place at 4° C. overnight.

ELISA assay. Remove from the 20° C. freezer any supernatant samples needing for the assay and leave at room temperature to thaw. Prepare the plate washer (Wellwash 4 Mk2) as follows: Insert control card into right side of machine and turn machine on. Make sure parameters on the card are set as follows: Dials: Soak×0.5 min=0, Pause=0, Washes=3, Volume×50 μL=4; Toggles: single, 12way, plate, stepoff, wash HI, dry, F1 off, F2 off, F dry. Empty waste reservoir if waste present. Replace dH₂O reservoir with 1×TBST reservoir. Make certain at least 500 mL/plate of TBST is in reservoir before starting. Press the <PRIME> button to flush the dH₂O from the system. With the “Wash Plate” in place, wash system by pressing <4> row button then <START> button. Plate washer should wash the first half of the plate 3 times then aspirate the plate leaving it dry.

Blocking. Remove adhesive plate film from plate to be washed and place on washer. Wash plate 3 times (press <8> then <START>). After washing, shake out any remaining TBST from plate with a sharp swing (do this after each wash from here on). Pipet 100 μL of blocking solution into each well using multichannel pipetter. Cover plate with adhesive plate film and leave at room temperature 1 hour.

Sample binding. If using samples of supernatant from a 96] well plate, briefly spin thawed sample plate in centrifuge at 2K rpm/2 mins/RT. Dilute any supernatant samples as needed. Use blocking solution to dilute so that 100 μL of diluted sample can be added per well. For duplicate assays with background controls, at least 400 μL of diluted sample will be needed. Wash blocked plate 3 times. Pipette samples onto plate according to plate diagram using 100 μL of sample/well. If needed, add (+) and (−) controls on plate (ex. 1:5000 dilution of mouse α-SEC-2 monoclonal antibody in blocking buffer for SEC-2 assay). Blank wells should have 100 μL of blocking solution added. Cover plate with adhesive plate film and place on plate shaker set for 1 hour at 450 rpm. To shake multiple plates, wrap a narrow strip of parafilm around plate stack before loading.

2° antibody binding. Make secondary antibody dilution. Use blocking solution and the appropriate antibody at the appropriate dilution. 100 μL is needed per well so 10 mL will be needed per plate. [For α-human IgG 2° Ab, use goat α-human IgG antibody at a dilution of 1:10,000 (1 μL 2° Ab/10 mL blocking solution). For the positive control mouse α-SEC-2 monoclonal antibody, use 1:10000 dilution of goat α-mouse IgG-AP 2° Ab]. Post sample binding, remove from shaker and remove adhesive films. Change wash dial on control card from 3 to 4 and wash plate 4 times. Pipet 100 μL of secondary antibody into each well. Seal plate with new adhesive film and put on plate shaker for 1 hour at 450 rpm.

Substrate addition. 5 minutes before 2° Ab binding is completed, prepare reactant. For 1 plate, mix 2 mL of 5× substrate buffer with 8 mL diH2O and 2 reactant tablets in a 15 mL culture tube. Mix by inverting until tablets are fully dissolved. Remove plate from mixer and remove adhesive films. Change wash dial on control card from 4 to 6 and wash plate 6 times. Add 100 μL of prepared reactant to each well of plate. Place fresh adhesive film on plate and place plate in drawer of desk beneath plate reader. Leave plate in drawer and monitor for color change from clear to yellow. The time for development may be from 30 minutes for an extremely strong reaction to 6 hours for a very weak reaction. It is ideal to read the plates when color is evident in some wells and before the solution becomes saturated.

Plate reading. When plates are ready for quantitation, make sure plate reader is turned on and the ScanIt RE for MSS2.2 software is open. Open the appropriate plate reading program and setup run if desired. Remove cover film from plate to be loaded. Load plate into machine and scan. Observe the results of the scan (Photometric and Statistics) to determine if additional scans are needed. If scanning is completed, remove plate, replace cover film, and place in drawer to reserve overnight. After all scans have been completed, turn off plate reader.

Reagents and Buffers:

Antigen: Staph Entertoxin C-2 Toxin Technologies, Inc. (CT222red)

Positive control antibody: anti-SEC g1 murine Mab: Toxin Technologies, Inc. (MC165)

Binding buffer (1×) 20 mM Tris-Cl, pH 8.5

TBST buffer (1×) 50 mM Tris, 0.9% NaCl (w:v), 0.1% Tween-20 (v:v), pH. to 7.5 with HCl. Dilute from 5×TBS stock using diH₂O, add Tween-20 and mix using stir bar for several minutes. It can be mixed in a glass bottle or the TBST Wellwash reservoir. A stirbar is left in the reservoir.

Blocking solution (1×) Pierce SuperBlock dry blend, TBS blocking buffer (prod #0037545). Add 1 packet of buffer powder to 200 mL of diH2O. Mix until dissolved. Store at 4° C. All procedures to be conducted in the fume hood to contain toxin. All waste products and consumables to be disposed of in biohazardous waste containers and autoclaved. Liquid waste to be treated with bleach at 10% prior to disposal. Use appropriate protective gear (gloves and safety goggles) during assay. Refer to SEC-specific IBC regulations prior to usage.

Time to completion: Plate coating (the day before assay) 30 minutes ELISA assay 4-8 hours plus development time (30 min-24 h)

PLGF ELISA

Binding of test antigen to assay plate. The day before, add to 1× binding buffer (1×DPBS, Gibco 14190) the PLGF antigen at 2 ug/mL. The amount of buffer to use is 5 mL per 96-well plate at 50 μL buffer/well. Using a multichannel pipettor, add 50 μL/well of the antigen-binding buffer mix to the test wells of a non-sterile, flat-bottomed 96-well plate (use CoStar EIA/RIA plate, no lid 96-well Easy Wash, prod #3369). For the control background wells, add 50 μL of 1× binding buffer (without antigen). Cover plate(s) with adhesive plate film and place at 4° C. overnight.

ELISA assay. Remove from the 20° C. freezer any supernatant samples needing for the assay and leave at room temperature to thaw. Prepare the plate washer (Wellwash 4 Mk2) as follows: Insert control card into right side of machine and turn machine on. Make sure parameters on the card are set as follows: Dials: Soak×0.5 min=0, Pause=0, Washes=3, Volume×50 μL=4; Toggles: single, 12way, plate, stepoff, wash HI, dry, F1 off, F2 off, F dry. Empty waste reservoir if waste present. Replace dH2O reservoir with 1×TBST reservoir. Make certain at least 500 mL/plate of TBST is in reservoir before starting. Press the <PRIME> button to flush the dH₂O from the system. With the “Wash Plate” in place, wash system by pressing <4> row button then <START> button. Plate washer should wash the first half of the plate 3 times then aspirate the plate leaving it dry. Blocking. Remove adhesive plate film from plate to be washed and place on washer. Wash plate 3 times (press <8> then <START>). After washing, shake out any remaining TBST from plate with a sharp swing (do this after each wash from here on). Pipet 100 μL of blocking solution into each well using multichannel pipetter. Cover plate with adhesive plate film and leave at room temperature 1 hour.

Sample binding. If using samples of supernatant from a 96-well plate, briefly spin thawed sample plate in centrifuge at 2K rpm/2 mins/RT. Dilute any supernatant samples as needed. Use blocking solution to dilute so that 100 μL of diluted sample can be added per well. For duplicate assays with background controls, at least 4004 of diluted sample will be needed. Wash blocked plate 3 times. Pipette samples onto plate according to plate diagram using 100 μL of sample/well. If needed, add (+) and (−) controls on plate (ex. 1:2000 dilution of mouse α-human PLGF monoclonal antibody in blocking buffer for PLGF assay). Blank wells should have 100 μL of blocking solution added. Cover plate with adhesive plate film and place on plate shaker set for 1 hour at 450 rpm. To shake multiple plates, wrap a narrow strip of parafilm around plate stack before loading.

2° antibody binding. Make secondary antibody dilution. Use blocking solution and the appropriate antibody at the appropriate dilution. 100 μL is needed per well so 10 mL will be needed per plate. For α-human IgG 2° Ab, use goat α-human IgG antibody at a dilution of 1:10,000 (1 μL 2° Ab/10 mL blocking solution). For the positive control mouse α-human PLGF monoclonal antibody, use 1:10000 dilution of goat α-mouse IgG-AP 2° Ab]. Post sample binding, remove from shaker and remove adhesive films. Change wash dial on control card from 3 to 4 and wash plate 4 times. Pipet 100 μL of secondary antibody into each well. Seal plate with new adhesive film and put on plate shaker for 1 hour at 450 rpm.

Substrate addition. 5 minutes before 2° Ab binding is completed, prepare reactant. For 1 plate, mix 2 mL of 5× substrate buffer with 8 mL diH₂O and 2 reactant tablets in a 15 mL culture tube. Mix by inverting until tablets are fully dissolved. Remove plate from mixer and remove adhesive films. Change wash dial on control card from 4 to 6 and wash plate 6 times. Add 100 μL of prepared reactant to each well of plate. Place fresh adhesive film on plate and place plate in drawer of desk beneath plate reader. Leave plate in drawer and monitor for color change from clear to yellow. The time for development may be from 30 minutes for an extremely strong reaction to 6 hours for a very weak reaction. It is ideal to read the plates when color is evident in some wells and before the solution becomes saturated.

Plate reading. When plates are ready for quantitation, make sure plate reader is turned on and the ScanIt RE for MSS2.2 software is open. Open the appropriate plate reading program and setup run if desired. Remove cover film from plate to be loaded. Load plate into machine and scan. Observe the results of the scan (Photometric and Statistics) to determine if additional scans are needed. If scanning is completed, remove plate, replace cover film, and place in drawer to reserve overnight. After all scans have been completed, turn off plate reader.

Reagents and Buffers:

Antigen: recombinant human PLGF PeproTech (100-06)

Positive control antibody: mouse anti-human PLGF Mab: R&D Systems (MAB264)

Binding buffer (1×) 1× Dulbecco's Phosphate Buffered Saline, Gibco (14190)

TBST buffer (1×) 50 mM Tris, 0.9% NaCl (w:v), 0.1% Tween-20 (v:v), pH. to 7.5 with HCl. Dilute from 5×TBS stock using diH₂O, add Tween-20 and mix using stir bar for several minutes. It can be mixed in a glass bottle or the TBST Wellwash reservoir. A stirbar is left in the reservoir.

Blocking solution (1×) Pierce SuperBlock dry blend, TBS blocking buffer (prod #0037545). Add 1 packet of buffer powder to 200 mL of diH₂O. Mix until dissolved. Store at 4° C. For long term storage (>1 week) add 100 mg sodium azide/200 mL.

Substrate (1×) Pierce phosphatase substrate kit (prod #37620). For 1 plate, make 10 mL as follows in a 15 mL culture tube: 2 mL 5×DEA substrate buffer, 8 mL diH2O, 2 PNPP tablets. Mix by inverting until tablets are fully dissolved.

Time to completion: Plate coating (the day before assay) 30 minutes ELISA assay 4-8 hours plus development time (30 min-24 h)

Ricin B ELISA

Binding of test antigen to assay plate. The day before, add to 1× binding buffer (1×DPBS, Gibco 14190) the ricin B chain antigen at 5 ug/mL. The amount of buffer to use is 5 mL per 96-well plate at 50 μL buffer/well. Using a multichannel pipettor, add 50 μL/well of the antigen-binding buffer mix to the test wells of a non-sterile, flat-bottomed 96-well plate (use CoStar EIA/RIA plate, no lid 96-well Easy Wash, prod #3369). For the control background wells, add 50 μL of 1× binding buffer (without antigen). Cover plate(s) with adhesive plate film and place at 4° C. overnight.

ELISA assay. Remove from the 20° C. freezer any supernatant samples needing for the assay and leave at room temperature to thaw. Prepare the plate washer (Wellwash 4 Mk2) as follows: Insert control card into right side of machine and turn machine on. Make sure parameters on the card are set as follows: Dials: Soak×0.5 min=0, Pause=0, Washes=3, Volume×50 μL=4; Toggles: single, 12way, plate, stepoff, wash HI, dry, F1 off, F2 off, F dry. Empty waste reservoir if waste present. Replace dH₂O reservoir with 1×TBST reservoir. Make certain at least 500 mL/plate of TBST is in reservoir before starting. Press the <PRIME> button to flush the dH2O from the system. With the “Wash Plate” in place, wash system by pressing <4> row button then <START> button. Plate washer should wash the first half of the plate 3 times then aspirate the plate leaving it dry.

Blocking. Remove adhesive plate film from plate to be washed and place on washer. Wash plate 3 times (press <8> then <START>). After washing, shake out any remaining TBST from plate with a sharp swing (do this after each wash from here on). Pipet 100 μL of blocking solution into each well using multichannel pipetter. Cover plate with adhesive plate film and leave at room temperature 1 hour.

Sample binding. If using samples of supernatant from a 96-well plate, briefly spin thawed sample plate in centrifuge at 2K rpm/2 mins/RT. Dilute any supernatant samples as needed. Use blocking solution to dilute so that 100 μL of diluted sample can be added per well. For duplicate assays with background controls, at least 4004 of diluted sample will be needed. Wash blocked plate 3 times. Pipette samples onto plate according to plate diagram using 100 μL of sample/well. If needed, add (+) and (−) controls on plate (ex. 1:5000 dilution of mouse α-ricinB monoclonal antibody in blocking buffer for ricin assay). Blank wells should have 100 μL of blocking solution added. Cover plate with adhesive plate film and place on plate shaker set for 1 hour at 450 rpm. To shake multiple plates, wrap a narrow strip of parafilm around plate stack before loading.

2° antibody binding. Make secondary antibody dilution. Use blocking solution and the appropriate antibody at the appropriate dilution. 100 μL is needed per well so 10 mL will be needed per plate. [For α-human IgG 2° Ab, use goat α-human IgG antibody at a dilution of 1:10,000 (1 μL 2° Ab/10 mL blocking solution). For the positive control mouse α-ricinB monoclonal antibody, use 1:10000 dilution of goat α-mouse IgG-AP 2° Ab]. Post sample binding, remove from shaker and remove adhesive films. Change wash dial on control card from 3 to 4 and wash plate 4 times. Pipet 100 μL of secondary antibody into each well. Seal plate with new adhesive film and put on plate shaker for 1 hour at 450 rpm.

Substrate addition. 5 minutes before 2° Ab binding is completed, prepare reactant. For 1 plate, mix 2 mL of 5× substrate buffer with 8 mL diH₂O and 2 reactant tablets in a 15 mL culture tube. Mix by inverting until tablets are fully dissolved. Remove plate from mixer and remove adhesive films. Change wash dial on control card from 4 to 6 and wash plate 6 times. Add 100 μL of prepared reactant to each well of plate. Place fresh adhesive film on plate and place plate in drawer of desk beneath plate reader. Leave plate in drawer and monitor for color change from clear to yellow. The time for development may be from 30 minutes for an extremely strong reaction to 6 hours for a very weak reaction. It is ideal to read the plates when color is evident in some wells and before the solution becomes saturated.

Plate reading. When plates are ready for quantitation, make sure plate reader is turned on and the ScanIt RE for MSS2.2 software is open. Open the appropriate plate reading program and setup run if desired. Remove cover film from plate to be loaded. Load plate into machine and scan. Observe the results of the scan (Photometric and Statistics) to determine if additional scans are needed. If scanning is completed, remove plate, replace cover film, and place in drawer to reserve overnight. After all scans have been completed, turn off plate reader.

Reagents and Buffers:

Antigen: ricin B chain Vector Laboratories (L-1290)

Positive control antibody: mouse anti-ricinB Mab: Santa Cruz Biotechnologies (sc-52197)

Binding buffer (1×) 1× Dulbecco's Phosphate Buffered Saline, Gibco (14190)

TBST buffer (1×) 50 mM Tris, 0.9% NaCl (w:v), 0.1% Tween-20 (v:v), pH. to 7.5 with HCl. Dilute from 5×TBS stock using diH2O, add Tween

]20 and mix using stir bar for several minutes. It can be mixed in a glass bottle or the TBST Wellwash reservoir. A stirbar is left in the reservoir.

Blocking solution (1×) Pierce SuperBlock dry blend, TBS blocking buffer (prod #0037545). Add 1 packet of buffer powder to 200 mL of diH₂O. Mix until dissolved. Store at 4° C. For long term storage (>1 week) add 100 mg sodium azide/200 mL.

Substrate (1×) Pierce phosphatase substrate kit (prod #37620). For 1 plate, make 10 mL as follows in a 15 mL culture tube: 2 mL 5×DEA substrate buffer, 8 mL diH₂O, 2 PNPP tablets. Mix by inverting until tablets are fully dissolved.

Time to completion: Plate coating (the day before assay) 30 minutes ELISA assay 4-8 hours plus development time (30 min-24 h)

IL6 ELISA

Binding of test antigen to assay plate. The day before, add to 1× binding buffer (1×DPBS, Gibco 14190) the IL-6 antigen at 5 ug/mL. The amount of buffer to use is 5 mL per 96-well plate at 50 μL buffer/well. Using a multichannel pipettor, add 50 μL/well of the antigen-binding buffer mix to the test wells of a non-sterile, flat-bottomed 96-well plate (use CoStar EIA/RIA plate, no lid 96-well Easy Wash, prod #3369). For the control background wells, add 50 μL of 1× binding buffer (without antigen). Cover plate(s) with adhesive plate film and place at 4° C. overnight.

ELISA assay. Remove from the 20° C. freezer any supernatant samples needing for the assay and leave at room temperature to thaw. Prepare the plate washer (Wellwash 4 Mk2) as follows: Insert control card into right side of machine and turn machine on. Make sure parameters on the card are set as follows: Dials: Soak×0.5 min=0, Pause=0, Washes=3, Volume×50 μL=4; Toggles: single, 12way, plate, stepoff, wash HI, dry, F1 off, F2 off, F dry. Empty waste reservoir if waste present. Replace dH2O reservoir with 1×TBST reservoir. Make certain at least 500 mL/plate of TBST is in reservoir before starting. Press the <PRIME> button to flush the dH2O from the system. With the “Wash Plate” in place, wash system by pressing <4> row button then <START> button. Plate washer should wash the first half of the plate 3 times then aspirate the plate leaving it dry.

Blocking. Remove adhesive plate film from plate to be washed and place on washer. Wash plate 3 times (press <8> then <START>). After washing, shake out any remaining TBST from plate with a sharp swing (do this after each wash from here on). Pipet 100 μL of blocking solution into each well using multichannel pipetter. Cover plate with adhesive plate film and leave at room temperature 1 hour.

Sample binding. If using samples of supernatant from a 96-well plate, briefly spin thawed sample plate in centrifuge at 2K rpm/2 mins/RT. Dilute any supernatant samples as needed. Use blocking solution to dilute so that 100 μL of diluted sample can be added per well. For duplicate assays with background controls, at least 4004 of diluted sample will be needed. Wash blocked plate 3 times. Pipette samples onto plate according to plate diagram using 100 μL of sample/well. If needed, add (+) and (−) controls on plate (ex. 1:5000 dilution of mouse α-human IL-6 monoclonal antibody in blocking buffer for IL-6 assay). Blank wells should have 100 μL of blocking solution added. Cover plate with adhesive plate film and place on plate shaker set for 1 hour at 450 rpm. To shake multiple plates, wrap a narrow strip of parafilm around plate stack before loading.

2° antibody binding. Make secondary antibody dilution. Use blocking solution and the appropriate antibody at the appropriate dilution. 100 μL is needed per well so 10 mL will be needed per plate. [For α-human IgG 2° Ab, use goat α-human IgG antibody at a dilution of 1:10,000 (1 μL 2° Ab/10 mL blocking solution). For the positive control mouse α-human IL-6 monoclonal antibody, use 1:10000 dilution of goat α-mouse IgG-AP 2° Ab]. Post sample binding, remove from shaker and remove adhesive films. Change wash dial on control card from 3 to 4 and wash plate 4 times. Pipet 100 μL of secondary antibody into each well. Seal plate with new adhesive film and put on plate shaker for 1 hour at 450 rpm.

Substrate addition. 5 minutes before 2° Ab binding is completed, prepare reactant. For 1 plate, mix 2 mL of 5× substrate buffer with 8 mL diH₂O and 2 reactant tablets in a 15 mL culture tube. Mix by inverting until tablets are fully dissolved. Remove plate from mixer and remove adhesive films. Change wash dial on control card from 4 to 6 and wash plate 6 times. Add 100 μL of prepared reactant to each well of plate. Place fresh adhesive film on plate and place plate in drawer of desk beneath plate reader. Leave plate in drawer and monitor for color change from clear to yellow. The time for development may be from 30 minutes for an extremely strong reaction to 6 hours for a very weak reaction. It is ideal to read the plates when color is evident in some wells and before the solution becomes saturated.

Plate reading. When plates are ready for quantitation, make sure plate reader is turned on and the ScanIt RE for MSS2.2 software is open. Open the appropriate plate reading program and setup run if desired. Remove cover film from plate to be loaded. Load plate into machine and scan. Observe the results of the scan (Photometric and Statistics) to determine if additional scans are needed. If scanning is completed, remove plate, replace cover film, and place in drawer to reserve overnight. After all scans have been completed, turn off plate reader.

Reagents and Buffers:

Antigen: recombinant human IL-6 GenScript (Z00372-1 mg)

Positive control antibody: mouse anti-human IL-6 Mab: PeproTech (500-M06)

Binding buffer (1×) 1× Dulbecco's Phosphate Buffered Saline, Gibco (14190)

TBST buffer (1×) 50 mM Tris, 0.9% NaCl (w:v), 0.1% Tween-20 (v:v), pH. to 7.5 with HCl. Dilute from 5×TBS stock using diH2O, add Tween

]20 and mix using stir bar for several minutes. It can be mixed in a glass bottle or the TBST Wellwash reservoir. A stirbar is left in the reservoir.

Blocking solution (1×) Pierce SuperBlock dry blend, TBS blocking buffer (prod #0037545). Add 1 packet of buffer powder to 200 mL of diH2O. Mix until dissolved. Store at 4° C. For long term storage (>1 week) add 100 mg sodium azide/200 mL.

Substrate (1×) Pierce phosphatase substrate kit (prod #37620). For 1 plate, make 10 mL as follows in a 15 mL culture tube: 2 mL 5×DEA substrate buffer, 8 mL diH₂O, 2 PNPP tablets. Mix by inverting until tablets are fully dissolved.

Time to completion: Plate coating (the day before assay) 30 minutes ELISA assay 4-8 hours plus development time (30 min-24 h)

Example 4 Results for Human B-Cells Secreting Monoclonal Antibodies Reactive with SEB, SEC-2, PLGF, and Ricin B Chain

Development of ELISAs that detect human IgG that is reactive with specific antigens. In order to screen immortalized tonsil repertoires for antibodies that are reactive with SEB, SEC2, PLGF, ricin subunit B, or IL6, the inventors developed enzyme linked immunosorbent assays (ELISAs). For each ELISA, the specific antigen was first bound to the plate, and then cell supernatants from the immortalized repertoires containing human IgG were applied to the wells. Nonspecific IgG was washed away, while antigen specific IgG bound to the antigen coated wells. The bound IgG was then detected with labeled anti-human IgG in the presence of a chromogenic substrate, which increased absorbance at OD405 nm, and was detected by spectrophotometry. Each ELISA required: 1) optimization of amount of antigen bound to plates; 2) optimization of detection antibodies; 3) optimization of buffer; 4) comparison with mouse monoclonal antibody binding, used as positive control. As an example, steps 3 and 4, optimization of buffers and comparison with mouse monoclonal antibody binding, used for the PLGF ELISA is shown in FIG. 36. Similar results were obtained for each ELISA. The optimized conditions for each were described in detail in the Materials and Methods section.

Creation of immortalized tonsil repertoires. Eleven tonsil repertoires were created and screened for reactivity with different antigens: TNSL-R, -S, -T, -V, -W, -X, -Y, -Z, -α, .β, γ. Each repertoire contained 7−21×10⁷ EBV immortalized cells that were plated into ten 96-well round-bottom plates, and induced to differentiate with soluble CD40 ligand (5 ng/ml), BAFF (10 ng/ml), and goat anti-human IgM F(ab′)₂ (1.62 ng/ml), as described in Materials and Methods. A summary of the characteristics of each repertoire can be found in Tables 7 and 9. In addition 3 immortalized tonsil repertoires that had previously been created and then stored frozen in liquid nitrogen, were thawed and cultured in two 24-well plates: TNSL-G, -H, -I (Tables 7 and 9).

TABLE 7 Summary of data on isolation of immortalized human B cells secreting monoclonal antibodies reactive with SEB. # of # of B sub- # of Treatment for SEB Date cells # of cloned possible inducing B cell specific Sample received (×107) plates wells clones differentiation IgG Status TNSL R Mar. 31, 2008 21 10 0 0 Anti-IgM Initially 1 well subcloned, 1 (Fab)2, positive, plate: CD4OL, BAFF reactivity (TR-9D8) lost Reactivity lost TNSL S Mar. 31, 2008 17 10 4 4 Anti-IgM Initially 3 well subcloned, 1 (Fab)2, positive, plate each: CD4OL, BAFF reactivity (TS 2B1, 8B12, 7C2) lost Reactivity lost in 3/3 plates TNSL T Apr. 28, 2008 7.2 9 0 0 Anti-IgM Negative Screening discontinued: (Fab′)2, negative at week 2 CD4OL, BAFF TNSL V May 2, 2008 8 9 1 1 Anti-IgM Positive 1 subcloned, 3 plates: (Fab12, (TV 6F7) CD4OL, BAFF Weak reactivity in 3/3 TNSL W May 14, 2008 14 10 0 0 Anti-IgM Negative Screening discontinued: (Fab′)2, negative at week 2 CD4OL, BAFF TNSL X May 19, 2008 11 10 2 strong + 3 5 Anti-IgM Positive 2 subcloned, 3 plates weak (Fab)2, each: (frozen) CD4OL BAFF (TX 8A8, TX 4H3) Strong reactivity in 6/6 TNSL Y Jun. 2, 2008 7 10 0 0 Anti-IgM Negative Screening discontinued: (Fab′)2, negative at day 10 CD4OL, BAFF TNSL Z Jun. 2, 2008 12.5 10 0 0 Anti-IgM Negative Screening discontinued: (Fab′)2, negative at day 10 CD4OL, BAFF TNSL α Jun. 6, 2008 7 10 0 0 Anti-IgM Negative Screening discontinued: (Fab′)2, negative at week 2 CD4OL, BAFF TNSL β Jun. 11, 2008 11 10 0 0 Anti-IgM (Fab′) Negative Screening discontinued: CD4OL, BAFF negative at week 2 TNSL γ Jun. 18, 2008 12 10 0 0 Anti-IgM Negative Screening discontinued: (Fab′)2, negative at week 2 CD4OL, BAFF TNSL a Jun. 6, 2008 7 10 0 0 Anti-IgM Negative Screening discontinued: (Fab′)2, negative at week 2 CD4OL, BAFF TNSL Jun. 11, 2008 11 10 0 0 Anti-IgM (Fab′) Negative Screening discontinued: 13 CD4OL, BAFF negative at week 2 TNSL y Jun. 18, 2008 12 10 0 0 Anti-IgM Negative Screening discontinued: (Fab′)2, negative at week 2 CD4OL, BAFF TNSL G Nov. 19, 6.5 2 × 24- 0 0 Anti-IgM Negative Screening discontinued: 2007 well (Fab′)2, negative at week 2 CD4OL, BAFF TNSL H Nov. 19, 5.2 2 × 24- 0 0 Anti-IgM Negative Screening discontinued: 2007 well (Fab′)2, negative at week 2 CD4OL, BAFF TNSL I Dec. 10, 5.0 2 × 24- 0 0 Anti-IgM Negative Screening discontinued: 2007 well (Fab′)2, negative at week 2 CD4OL, BAFF

TABLE 9 Summary of data on isolation of immortalized human B cells secreting monoclonal antibodies reactive with SEC-2 # of # of sub- # of Treatment for SEC-2 Date B cells # of cloned possible inducing B cell specific Sample received (×107) plates wells clones differentiation IgG Status TNSL R Mar. 31, 2008 21 10 2 2 Anti-IgM Positive 2 subclones, 1 plate each: (Fab12, but lost (TR 10A4, TR 10E12) CD4OL, BAFF Reactivity lost in 2/2 subclones TNSL S Mar. 31, 2008 17 10 1 1 Anti-IgM Positive 1 subclone, 1 plate: (Fab12, but lost (TS 6C5) CD4OL, BAFF Reactivity lost in 4/4 subclones TNSL T Apr. 28, 2008 7.2 9 0 0 Anti-IgM Negative Screening discontinued: (Fab′)2, negative at week 2 CD4OL, BAFF TNSL V May 2, 2008 8 9 2 2 Anti-IgM Positive 1 subcloned, 3 plates (Fab12, (TV bB2) CD4OL, BAFF Weak reactivity in 1/3 plates TNSL W May 14, 2008 14 10 0 0 Anti-IgM Negative Screening discontinued: (Fab)2, negative at week 2 CD4OL, BAFF TNSL X May 19, 2008 11 10 0 0 Anti-IgM Negative Screening discontinued: (Fab′)2, negative at week 2 CD4OL, BAFF TNSL Y Jun. 2, 2008 7 10 0 0 Anti-IgM Negative Screening discontinued: (Fab′)2, negative at day 10 CD4OL, BAFF TNSL Z Jun. 2, 2008 12.5 10 0 0 Anti-IgM Negative Screening discontinued: (Fab′)2, negative at day 10 CD4OL, BAFF TNSL α Jun. 6, 2008 7 10 0 0 Anti-IgM Negative Screening discontinued: (Fab′)2, negative at week 2 CD4OL, BAFF TNSL β Jun. 11, 2008 11 10 0 0 Anti-IgM Negative Screening discontinued: (Fab′)2, negative at week 2 CD4OL, BAFF TNSL y Jun. 18, 2008 12 10 0 0 Anti-IgM Negative Screening discontinued: (Fab′)2, negative at week 2 CD4OL, BAFF TNSL G Nov. 19, 2007 6.5 2 × 24- 0 0 Anti-IgM Negative Screening discontinued: well (Fab′)2, negative at week 2 CD4OL, BAFF TNSL H Nov. 19, 2007 5.2 2 × 24- 0 0 Anti-IgM Negative Screening discontinued: well (Fab′)2, negative at week 2 CD4OL, BAFF TNSL I Dec. 10, 2007 5.0 2 × 24- 0 0 Anti-IgM (Fab)2 Negative Screening discontinued: well CD4OL, BAFF negative at week 2

Screening of immortalized tonsil repertoires. Eleven tonsil repertoires, and 3 thawed repertoires were screened for binding to SEB (Table 7), and SEC2 (Table 9). Ten of the new repertoires (TNSL-R, -S, -V, -W, -X, -Y, -Z, -α, -β, -γ), and 3 thawed repertoires were screened for PLGF binding (Table 11). Nine of the new repertoires (TNSL-R, -S, -V, -W, -X, -Z, -α, -β, -γ), and 3 thawed repertoires were screened for ricin subunit B binding (Table 13). Four of the new repertoires (TNSL-R, -S, -β, -γ) were screened for IL6 binding (Table 15). Fewer repertoires were screened for IL6 because it took longer to optimize that ELISA.

TABLE 11 Summary of data on isolation of immortalized human B cells secreting monoclonal antibodies reactive with PLGF # of # of B sub- # of Treatment for PLGF Date cells # of cloned possible inducing B cell specific Sample received (×107) plates wells clones differentiation IgG Status TNSL R Mar. 31, 2008 21 10 0 0 Anti-IgM Negative Screening (Fab′)2, discontinued: CD4OL, BAFF negative at week 3 TNSL S Mar. 31, 2008 17 10 0 0 Anti-IgM Negative Screening (Fab′)2, discontinued: CD4OL, BAFF negative at week 3 TNSL V May 2, 2008 8  9 0 0 Anti-IgM (Fab′)2, Negative Screening CD4OL, BAFF discontinued: negative at week 2 TNSL W May 14, 2008 14 10 1 1 Anti-IgM Positive 1 subclone, 5 plates: (Fab12, (TW 1E12)Weak CD4OL, BAFF reactivity in 215 plates TNSL X May 19, 2008 11 10 0 0 Anti-IgM (Fab′)2, Negative Screening CD4OL, BAFF discontinued: negative at week 2 TNSL Y Jun. 2, 2008 7 10 0 0 Anti-IgM Negative Screening (Fab′)2, discontinued: CD4OL, BAFF negative at day 10 TNSL Z Jun. 2, 2008 12.5 10 2 2 Anti-IgM Positive 2 subclones, 2 plates (Fab12, each: CD4OL, BAFF (TZ 3B10, TZ 5F9) TNSL α Jun. 6, 2008 7 10 0 0 Anti-IgM Negative Screening (Fab′)2, discontinued: CD4OL, BAFF negative at week 2 TNSL β Jun. 11, 2008 11 10 0 0 Anti-IgM Negative Screening (Fab′)2, discontinued: CD4OL, BAFF negative at week 2 TNSL γ Jun. 18, 2008 12 10 0 0 Anti-IgM Negative Screening (Fab′)2, discontinued: CD4OL, BAFF negative at week 2 TNSL G Nov. 19, 2007 6.5 2 × 24- 0 0 Anti-IgM Negative Screening well (Fab′)2, discontinued: CD4OL, BAFF negative at week 2 TNSL H Nov. 19, 2007 5.2 2 × 24- 0 0 Anti-101 Negative Screening well (Fab′)2, discontinued: CD4OL, BAFF negative at week 2 TNSL I Dec. 10, 2007 5.0 2 × 24- 0 0 Anti-IgM Negative Screening well (Fab′)2, discontinued: CD4OL, BAFF negative at week 2

TABLE 13 Summary of data on isolation of immortalized human B cells secreting monoclonal antibodies reactive with ricin B chain # of sub- # of Treatment for Ricin B Date # of B # of cloned possible inducing B cell specific Sample received cells (×107) plates wells clones differentiation IgG Status TNSL R Mar. 31, 2008 21 10 0 0 Anti-IgM Negative Screening (Fab′)2, discontinued: CD40L, BAFF negative at week 3 TNSL S Mar. 31, 2008 17 10 0 0 Anti-IgM Negative Screening (Fab′)2, discontinued: CD4OL, BAFF negative at week 3 TNSL V May 2, 2008 8  9 0 0 Anti-IgM Negative Screening (Fab′)2, discontinued: CD4OL, BAFF negative at week 2 TNSL W May 14, 2008 14 10 0 Anti-IgM Negative Screening (Fab′)2, discontinued: CD4OL, BAFF negative at week 2 TNSL X May 19, 2008 11 10 0 0 Anti-IgM Negative Screening (Fab′)2, discontinued: CD4OL, BAFF negative at week 2 TNSL Z Jun. 2, 2008 12.5 10 2 2 Anti-IgM Positive 2 subclones, 5 plates (Fab′)2, each: CD4OL, BAFF (TZ 7B8, TZ 6F10) TNSL α Jun. 6, 2008 7 10 0 0 Anti-IgM Negative Screening (Fab′)2, discontinued: CD4OL, BAFF negative at week 2 TNSL β Jun. 11, 2008 11 10 0 0 Anti-IgM Negative Screening (Fab′)2, discontinued: CD4OL, BAFF negative at week 2 TNSL γ Jun. 18, 2008 12 10 0 0 Anti-IgM Negative Screening (Fab′)2, discontinued: CD4OL, BAFF negative at week 2 TNSL G Nov. 19, 2007 6.5 2 × 24- 0 0 Anti-IgM Negative Screening well (Fab′)2 discontinued: CD4OL, BAFF negative at week 2 TNSL H Nov. 19, 2007 5.2 2 × 24- 0 0 Anti-IgM Negative Screening well (Fab′)2 discontinued: CD4OL, BAFF negative at week 2 TNSL I Dec. 10, 2007 5.0 2 × 24- 0 0 Anti-IgM Negative Screening well (Fab′)2 discontinued: CD4OL, BAFF negative at week 2

TABLE 15 Summary of data on isolation of immortalized human B cells secreting monoclonal antibodies reactive with IL-6 # of Treatment for # of B sub- # of inducing B IL-6 Date cells # of cloned possible cell specific Sample received (×10⁷) plates wells clones differentiation IgG Status TNSL R Mar. 31, 2008 21 10 0 0 Anti-IgM Negative Screening (Fab′)2, discontinued: CD40L, BAFF negative at week 3 TNSL S Mar. 31, 2008 17 10 0 0 Anti-IgM Negative Screening (Fab′)2, discontinued: CD40L, BAFF negative at week 3 TNSL β Jun. 11, 2008 11 10 0 0 Anti-IgM Negative Screening (Fab′)2, discontinued: CD40L, BAFF negative at week 2 TNSL γ Jun. 18, 2008 12 10 0 0 Anti-IgM Negative Screening (Fab′)2, discontinued: CD40L, BAFF negative at week 2

Isolation of SEB reactive immortalized cell lines. Culture supernatants for all 11 new tonsil repertoires were screened for SEB reactivity between 10d and 18d subsequent to immortalization (summarized in Table 7). An example of the rapid screening strategy used to detect wells with reactive IgG is shown in FIG. 37. Tonsil repertoire TNSL-X (TX) supernatants from 10 96-well plates containing a total of 960 wells were screened with 2 ELISAs containing pooled supernatants from corresponding wells on each of the 10 plates, e.g., well A1 pools, (FIG. 37A), and pooled supernatants from all of the wells on each plate (plate pools, FIG. 37B). FIG. 37A indicated that cells in wells A8 and H3 on one of the 10 plates was reactive with SEB. FIG. 37B indicated that TX plates 2 and 4 contained cells that were SEB reactive. Combining these data in FIG. 37C, the inventors tested wells A8 and H3 on TX plates 4 and 8. The results indicated that well A8 on plate 8 (TX-8A8), and well H3 on plate 4 (TX-4H3) contained the activity. These wells were thus chosen for primary subcloning analysis. As can be seen in Table 8, TX-8A8 and TX-4H3 were subcloned initially on Jun. 4, 2008 into 3 96-well plates each, containing 1,000 cells per well.

TABLE 8 Summary of subcloning of immortalized human B cells secreting monoclonal antibodies reactive with SEB. Possible Subclone Date # of cells/ Unique sib Subclone Origin stage subcloned plates well clone clones Status TS 2B1 TNSL-S primary Apr. 29, 2008 1 100 yes none Lost reactivity 2B1 TS 8B12 TNSL-S primary Apr. 29, 2008 1 100 yes none Lost reactivity 8B12 TS 7C2 TNSL-S primary Apr. 29, 2008 1 100 yes none Lost reactivity 7C2 TR 9D8 TNSL-R primary Apr. 29, 2008 1 100 yes none Lost reactivity 9D8 TV 6F7 TNSL-V primary May 29, 2008 3 1000 yes none Moderate reactivity in 6F7 3/3 plates, 3 wells subloned 6123/08 TV 6F7 TNSL-V secondary Jun. 23, 2008 2 50 no 3E2, 3E4 Characterization 2H6 6F7 underway 2H6 TV 6F7 TNSL-V secondary Jun. 23, 2008 2 50 no 2H6, 3E4 Characterization 3E2 6F7 underway 3E2 TV 6F7 TNSL-V secondary Jun. 23, 2008 2 50 no 2H6, 3E2 Characterization 3E4 6F7 underway 3E4 TX 8A8 TNSL-X primary Jun. 4, 2008 3 1000 yes none Strong reactivity in 3/3 8A8 plates 3 wells subcloned TX 8A8 TNSL-X secondary Jun. 23, 2008 2 50 no 3F4, 3D7 Characterization 106 8A8 underway 106 TX 8A8 TNSL-X secondary Jun. 23, 2008 2 50 no 1C6, 3D7 Characterization 3F4 8A8 underway 3F4 TX 8A8 TNSL-X secondary Jun. 23, 2008 2 50 no 1C6, 3F4 Characterization 3D7 8A8 underway 3D7 TX 4H3 TNSL-X primary Jun. 4, 2008 3 1000 yes none Strong confirmed 4H3 reactivity in 3/3 plates, 3 secondary subclones made TX 4H3 TNSL-X secondary Jun. 21, 2008 2 50 no 3C6, 3D8 Characterization 1E7 4H3 underway 1E7 TX 4H3 TNSL-X secondary Jun. 21, 2008 2 50 no 1E7, 3D8 Characterization 3C6 4H3 underway 3C6 TX 4H3 TNSL-X secondary Jun. 21, 2008 2 50 no 1E7, 3C6 Characterization 3D8 4H3 underway 3D8

As can be seen in FIG. 38B, after 8 days in culture each of these plates contained SEB reactive cells. After 2 weeks in culture, individual wells from each plate were tested for SEB reactivity (FIG. 40 and FIG. 41). Three TX-4H3 wells with the highest reactivity (TX-1E7, -3C6, -3D8, FIG. 40) were chosen for a secondary round of subcloning on Jun. 23, 2008, in which 2 plates were created containing 50 cells per well (Table 8). In addition, three TX-8A8 wells with the highest reactivity (TX-8A8-106, -3D7, -3F4, FIG. 41) were chosen for a secondary round of subcloning on Jun. 23, 2008, in which 2 plates were created containing 50 cells per well (Table 8). Cells are currently growing to sufficient levels to test for SEB reactive IgG in individual wells. As can be seen in Table 7 and FIG. 38A, SEB reactive cells were detected in three other repertoires (TNSL-R, -S, -V). Wells containing the reactive cells (TS-2B1, -8B12, TS-7C2, TR-9D8, TV-6F7) were subcloned, and reactivity was detected in cells from the TV-6F7 plates, but was lost from the TS-8B12, TS-7C2 and TR-9D8 cell lines (FIG. 38B). Three TV6F7 wells with the highest reactivity (TV-6F7-2H6, -3E2, -3E4, FIG. 39) were chosen for a secondary round of subcloning on Jun. 23, 2008, in which 2 plates were created containing 50 cells per well (Table 8). Cells are currently growing to sufficient levels to test for SEB reactive IgG in individual wells.

Isolation of SEC2 reactive immortalized cell lines. As can be seen in Table 9 and FIG. 42, SEC2 reactive cells were detected in three tonsil repertoires (TNSL-R, -S, and -V). Wells containing the reactive cells (TR-10A4, TR-10E12, TS-6C5, and TV-bB2) were subcloned, and reactivity was detected in cells from 1 of 3 of the TV-bB2 plates (FIG. 43A), but was lost from the TR-10A4, TR-10E12, TS-6C5 plates (FIG. 42B). Two TV6F7 wells with the highest reactivity (TVbB2 2E1, 2F2, FIG. 43B) were chosen for a secondary round of subcloning on Jun. 23, 2008, in which 2 plates were created containing 50 cells per well (Table 10).

TABLE 10 Summary of subcloning of immortalized human B cells secreting monoclonal antibodies reactive with SEC₂ Possible Subclone Date # of cells/ Unique sib Subclone Origin stage subcloned plates well clone clones Status TR 10A4 TNSL-R primary Apr. 29, 2008 1 100 yes none Lost reactivity 10A4 TR 10E12 TNSL-R primary Apr. 29, 2008 1 100 yes none Lost reactivity 10E12 TS 6C5 TNSL-S primary Apr. 29, 2008 1 100 yes none Lost reactivity 6C5 TV bB2 TNSL-V primary May 29, 2008 3 500 yes none Weak reactivity in bB2 1/3 plate pools, 2 secondary TV bB2 TNSL-V secondary Jun. 23, 2008 2 50 no 2F2 Characterization 2E1 bB2 underway 2E1 TV bB2 TNSL-V secondary Jun. 23, 2008 2 50 no 2E1 Characterization 2F2 bB2 underway 2F2

Isolation of PLGF reactive immortalized cell lines. As can be seen in Table 11 and FIG. 44 and FIG. 46, PLGF reactive cells were detected in two tonsil repertoires (TNSL-W, and -Z). Wells containing the reactive cells (TW-1E12, FIG. 44; TZ-3B10 and TZ-5F9, FIG. 46) were subcloned. Two of 5 subcloned TW-1E12 plates were PLGF reactive (FIG. 45A). Individual wells on these plates were screened and 3 wells with the highest reactivity (TW 2E3, 2G9, 5A10) were chosen for a secondary round of subcloning on Jun. 23, 2008, in which 2 plates were created for each containing 50 cells per well (Table 12). Cells are currently growing to sufficient levels to test for PLGF reactive IgG in individual wells.

TABLE 12 Summary of subcloning of immortalized human B cells secreting monoclonal antibodies reactive with PLGF. Possible Subclone Date # of cells/ Unique sib Subclone Origin stage subcloned plates well clone clones Status TW 1E12 TNSL-W primary May 29, 2008 5 1000 yes none Weak reactivity in 1E12 2/5 plate pools, 3 secondary TW 1E12 TNSL-W secondary Jun. 23, 2008 2 50 no TW 1E12 Characterization 2E3 1E12 2E3 2G9, TVV underway 1E12 5A10 TW 1E12 TNSL-W secondary Jun. 23, 2008 2 50 no TVV Characterization 2G9 1E12 2G9 1E12 underway 2E3, TW 1E12 5A10 TW 1E12 TNSL-W secondary Jun. 23, 2008 2 50 no TW 1E12 Characterization 5A10 1E12 5A10 2G9, TW underway 1E12 2E3 TZ 3B10 TNSL-Z primary Jun. 13, 2008 3 1000 yes none Characterization 3B10 underway TZ 5F9 TNSL-Z primary Jun. 13, 2008 3 1000 yes none Characterization 5F9 underway

Isolation of ricin subunit B reactive immortalized cell lines. As can be seen in Table 13 and FIG. 47C, ricin subunit B reactive cells were detected in two wells of tonsil repertoire TNSL-Z (TZ-7B8 and TZ-6F10). Wells containing the reactive cells were subcloned on Jun. 21, 2008, 5 96-well plates each containing 50 cells per well (Table 14). Individual wells on these plates were screened on Jul. 14, 2008 and wells with the highest reactivity (TZ-7B8-1A12, -1E3, -2A1, -2A3, -4A1, FIG. 48) and (TZ-6F10 1C3, 1D6, 1F11, 2F2, 2G2, 3E1, 4H4, 4G6 5D7, FIG. 49) were chosen for a secondary round of subcloning, and for sequencing.

TABLE 14 Summary of subcloning of immortalized human B cells secreting monoclonal antibodies reactive with ricin B chain. Possible Subclone Date # of cells/ Unique sib Subclone Origin stage subcloned plates well clone clones Status TZ 7B8 TNSL-Z primary Jun. 21, 2008 5 50 yes none Positive 7B8 wells detected on 3/5 plates, screened Jul. 14, 2008 TZ 6F10 TNSL-Z primary Jun. 21, 2008 5 50 yes none Positive 6F10 wells detected on 4/5 plates, screened Jul. 14, 2008

Characterization of Ricin subunit B reactive cells TZ-6F10-4H4 and TZ-7B8-2A3. Two weeks after the secondary round of subcloning (25-500 cells per well), culture supernatant from individual wells was tested in triplicate for Ricin subunit B reactivity by ELISA. As can be seen in FIG. 58A, 12/20 wells containing secondary subcloned cells had variable levels of ricin B reactivity. Cells in wells TZ-6F10-4H4 and TZ-7B8-2A3 were chosen for immunoglobulin sequencing analysis. RT-PCR was performed using the primers described in FIG. 54A, as described previously. In each well, 2 light chain and heavy chain sequences were identified, consisting of λ1/3 and λ6, V_(H1) and V_(H3). PCR amplification products were sequenced. Sequencing indicated that the light chain immunoglobulin variable region for TZ-6F10-4H4 was composed of IGLV048 and IGLJ03*2 gene segments (FIG. 59A) (SEQ ID NOS:41 and 42). The V_(H3) heavy chain immunoglobulin variable region was composed of IGHV035 (FIG. 59B) (SEQ ID NOS:45 and 46). While the light chain region had >99% homology to germline sequences, the heavy chain region was hypermutated with 89% V_(H) germline homology; the obtained sequences were compared against the germline sequences and are presented in FIGS. 59A and B. The complentarity determining regions of the heavy and light chains are identified in FIG. 59F. Sequencing indicated that the λ3 light chain immunoglobulin variable region for TZ-7B8-2A3 was composed of IGLV063 and IGLJ03*2 gene segments (FIG. 59C) (SEQ ID NOS:49 and 50). A second λ6 light chain sequence was identified in cells in well TZ-7B8-2A3, composed of ILGV048 and IGLJ3*02 gene segments (FIG. 59D) (SEQ ID NOS:52 and 53). The V_(H1) heavy chain immunoglobulin variable region was composed of IGHV157, IGHD3-10*2, IGHJ04*2 (FIG. 59E) (SEQ ID NOS:57 and 58). While the light chain regions had >98% homology to germline sequences, the heavy chain region was hypermutated with 96% V_(H) germline homology, 46% D_(H) and 81% J_(H) homology to germline; the obtained sequences compared against the germline sequences are presented in FIGS. 59C-E. The complentarity determining regions of the heavy and light chains are identified in FIG. 59F (SEQ ID NOS:60, 61, 62, 63, and 64).

Screening for IL6 reactive immortalized cell lines. As can be seen in Table 15, four immortalized cell lines were tested for IL6 reactivity, and so far there have been no IL6 specific cell lines detected.

Example 5 Materials & Methods for Human B-Cells Secreting Antibodies Reactive with H5 HA

Generation and analysis of tonsil and peripheral blood derived B cell repertoires. Generation of concentrated EBV stocks and preparation of B cells from tonsil tissue and peripheral blood samples have been described previously. For induction of differentiation of EBV immortalized B cells, complete RPMI medium containing soluble CD40 ligand (5 ng/ml), BAFF (10 ng/ml), and goat anti-human IgM F(ab′)₂ (1.62 ng/ml) were used, as previously described.

Sample collection for ELISA analysis. Collection and screening of sample culture supernatants for H5 HA reactivity by ELISA have been modified as follows. Culture supernatants were collected into corresponding wells on a 96-well plate on day 10 post-transduction at 100 μl from each well, and aliquots were pooled (30 μl of supernatant from all wells on each plate) and screened by ELISA for H5 HA reactivity. The culture supernatant was replaced with 100 μl fresh RPMI medium containing CD40L, BAFF and anti-human IgM(Fab′)₂. If H5 HA reactivity was detected in pooled wells, each of the individual wells contributing to the pool was subcloned into 5 new wells to preserve viability while the identity of the positive well was confirmed by additional ELISA experiments. Once an individual well containing H5 HA reactive IgG had been identified in the rapid screening strategy, cells from that well were counted, and 50-80% of them were subcloned into 96-well plates (˜500 cells per well, depending upon the count), while the remainder were frozen. At various times after subcloning, supernatants were collected as outlined above and rapid screening analysis was repeated. This was followed by additional rounds of limiting dilution subcloning and screening. Clonality was assumed when at the lowest dilution, all wells on the plate were producing anti-H5 HA reactive IgG.

H5 HA and HIS-tagged H5 HA ELISA. His tagged recombinant H5 HA (strain H5N1 A/Vietnam/1203/2004) was obtained from Immune Technology Corp (# IT-003-0051p). This protein (H5 a.a. 18-530) has N-terminal 6 histidine (6×His) tag and a deletion at the HA cleavage site (ΔRRRKKR). His-tagged H5 HA was prepared in a neutral pH binding buffer (1×DPBS, pH 7.2) at 2 μg/ml for coating wells of 96-well ELISA plates (50 μl per well); sealed plates were allowed to bind overnight at 4° C. Non-specific binding for each sample and control was evaluated in triplicate by comparing results obtained from H5 HA coated wells vs. an equal number of uncoated wells that received binding buffer only. Next day, the plates were washed, blocked with a neutral pH blocking solution (SuperBlock-TBS, pH 7.4, from Pierce) plus 0.1% Tween 20, and incubated with samples or controls (100 μl per well) in triplicate wells. Controls consisted of human serum from volunteer (V5), previously found to be H5 HA reactive (diluted 1:500 in RPMI culture medium), and nonreactive purified human IgG (500 ng per 0.1 ml RPMI culture medium, Sigma). After extensive washes, alkaline phosphatase-labeled goat anti-human IgG (Southern) was added to each well, followed by colorimetric substrate reaction and detection. Average OD₄₀₅ values±standard deviations (n=3) for H5 HA binding (with average non-specific binding subtracted) are shown in all graphs.

Enrichment of cell populations expressing anti-H5 HA Ig using magnetic beads coupled to HIS-tagged H5 HA. Two different bead systems were employed. Amounts of reagents are given per 1×10⁶ cells to be screened, and were changed accordingly with different cell numbers. For THE™ Anti-His MagBeads (GenScript Corporation, #L00275), 0.5 mg (50 μl of stock) beads were washed 3× with 2 ml cold DPBS, and re-suspended in 0.2 ml cold Washing Buffer 1 (DPBS plus 0.2% BSA and 20 mM EDTA). Washed beads were mixed on ice with 0.5 μg of HIS-tagged H5 HA and incubated on ice with shaking for 1 hour, then washed twice with WB1. For the MagnaBead® Biotin Binder (Invitrogen, #110.47), 15 μl of beads (at 4×10⁸ beads per ml) are washed 3× with cold DPBS and re-suspended in 0.2 ml cold WB1. Beads are mixed on ice with 1 μg of THE™ Anti-His mAb[biotin] (GenScript, #A00613) and 1 μg HIS-tagged H5 HA and incubated on ice with shaking for 1 hour, then washed twice with WB1. For either bead::his-H5 HA complex, 1×10⁶ cells that have been washed 3× with DPBS are resuspended in 0.2 ml of WB1 and combined with the bead complex. The tube is shaken on ice for 30 minutes. The suspension is brought to 10 ml with ice-cold WB1 and placed in the EasySep magnet for a 3 min separation. The supernatant containing unbound cells (referred to as flow-through or FT) is collected, and the bead-cell retentate is washed twice with 10 ml of WB1. Next, 3 ml of room-temperature trypsin-EDTA solution (Mediatech Cellgro #21-053-Cl) is added and incubated for 5 min at RT. Then, 7 ml of complete culture media is added to inactivate trypsin, and the cells no longer attached to beads (trypsin wash fraction) are collected. The beads are washed twice with 10 ml WB1, and re-suspended in 1 ml of complete culture media (trypsin bead fraction). The FT and trypsin wash fractions are counted, centrifuged for 7 min at 1600 rpm, re-suspended in complete RPMI media, and dispensed into wells of a 96-well plate at 1×10⁴ to 5×10⁴ cells per well.

Identification of IgG subtypes. TN-6G7-7F8-2G7 culture supernatants were collected and dispensed into wells of a 96-well ELISA plate pre-coated with anti-human IgG and blocked with SuperBlock plus 0.1% Tween-20, as described in previous sections. After blocking, plates were washed extensively, then incubated with 100 μl of one of the four subtype-specific alkaline phoshatase—labeled murine monoclonal antibodies: anti-Hu IgG₁ (Invitrogen 05-3322), anti-Hu IgG₂ (Invitrogen 05-3522), anti-Hu IgG₃ (Invitrogen 05-3622), and anti-Hu IgG₄ (Invitrogen 05-3722). All antibodies were diluted in the block solution at 1:250. One hour incubation with antibodies was followed by colorimetric substrate reaction and detection. Average OD₄₀₅ values±standard deviations (n=3) were reported.

Analysis of the heavy and light chain variable region sequences of clone TN-6G7-7F8-2G7. Total RNA was extracted from approximately 10⁵-10⁶ cells using RNEasy protocol (Qiagen, #74104) with QIAshredder columns (Qiagen, #79654). RNA was converted to cDNA with the High Capacity cDNA Reverse Transcription Kit according to manufacturer's instructions (Applied Biosystems, #4368813) and analyzed by PCR for light and heavy chain type content using a set of primers adapted from Welschof et al. (1995) (see Figure x A). All forward primers incorporated an XbaI restriction site, while the reverse primers incorporated a SalI restriction site. PCR products were analyzed on 1% agarose gel (Figure x B). Reactions that resulted in detectable product were scaled up using the proofreading Accuzyme™ Mix kit (Bioline, # BIO-25027). PCR products were gel-purified using QIAquick Gel Extraction Kit (Qiagen, #28704), and a portion of each was submitted for sequencing to the MUSC DNA Core Facility with the original forward and reverse PCR primers. The remainder of each product was digested with XbaI and SalI (New England Biolabs), and cloned into XbaI/SalI digesteda similarly digested pSP73 plasmid (Promega, # P2221) for subsequent subcloning into mammalian expression vectors. Forward and reverse DNA sequences were aligned using Vector NTI (Invitrogen) ALIGN function, and combined corrected sequences were generated. These were analyzed using VBASE2 online software (Retter et al., 2005). Sequence numbering and motif alignments were performed according to Kabat standards (Johnson and Wu, 2000).

Example 6 Results For Human B-Cells Secreting Antibodies Reactive with H5 HA

Derivation of TN-6G7-7F8-2G7 cells. Human tonsil derived immortalized B cell repertoires were created as summarized in Table 16. All were screened for H5N1 hemagglutinin (H5 HA) reactivity at 10-14 days post-infection with Epstein-Barr virus (EBV). TN-6G7-7F8-2G7 cells were derived from tonsil repertoire TNSL-N (highlighted in yellow on Table 16). Culture supernatants were screened using the rapid screening ELISA method comprised of testing plate pools (pooled aliquots of culture supernatants derived from all wells in a single plate) and well pools (pooled aliquots from a particular well in same location on all 10 plates). As shown in FIG. 50, correlation of these data allowed for rapid identification of individual positive wells. As seen in FIG. 50A, ELISA analysis of culture supernatant from pooled wells indicated that H5 HA reactive IgG was found in well G7 on at least one of the 10 plates. FIG. 50B indicated that the reactivity was highest on plate 6. Verification of reactivity in culture supernatant from positive wells was conducted the following day. The ELISA was performed in triplicate with background binding to the plate (in the absence of H5 HA antigen) subtracted from the results. FIG. 50C indicated that plate 6 well G7 had the highest reactivity; thus, cells from well 6G7 were subcloned at 500 cells/well into ten 96-well plates, referred to as the primary round of subcloning. Two weeks later, culture supernatants from the subcloned cells were screened for H5 HA reactivity using a similar rapid screening strategy (FIG. 51). As can be seen in FIG. 51A, H5 HA reactivity was identified in multiple wells, with C8 and F8 having the highest reactivity. FIG. 51B indicated that significant H5 HA reactivity was detected on plates 2, 3, 5, 7 and 8; therefore culture supernatants from wells C8 and F8 were tested on each of these plates. As can be seen in FIG. 51C, wells 2C8, 8C8, and 7F8 contained the activity, with well 7F8 having the highest reactivity. Cells from that well were therefore subcloned at 500 cells per well into two plates, referred to as the secondary round of subcloning. Three weeks later, culture supernatants from wells pools from both plates were screened by ELISA for H5 HA reactivity. As can be seen in FIG. 52A, multiple wells were positive, with well G7 having the highest reactivity. FIG. 52B indicated that the strongest reactivity derived from culture supernatant in plate 2 well G7; thus, cells from this well were subcloned at 50 cells per well into two 96-well plates, referred to as the tertiary round of subcloning. Fungal contamination four weeks later necessitated that the process be repeated using an aliquot of frozen cells derived from the same well. Four weeks later, it was found that all wells on both subcloned plates were H5 HA reactive, indicative of clonality FIG. 53A. The subcloning strategy was summarized in Table 17.

TABLE 16 Summary of data on isolation of immortalized human B cells secreting antibodies reactive with H5 HA # of # of # of sub- Treatment for H5 HA Date B cells # of cloned possible inducing B cell specific Sample received (×107) plates wells clones differentiation IgG Status PBMC Jan. 16, 2007 0.2 3 1 0 Anti-IgM (Fab)2, Positive Subcloned 1 well: A1 IL-4, IL6 originally PA1-2D11 lost reactivity PBMC B Feb. 16, 2007 0.2 3 0 0 Anti-19M (Fab′)2, Negative Screening discontinued: IL-4, IL6 negative at week 3 PBMC Mar. 14, 2007 0.6 6 3 0 Anti-IgM (Fab)2, Positive Subcloned 3 wells; A2 CD4OL, BAFF originally lost reactivity PBMC C Sep. 22, 2007 3 10 1 1 Anti-IgM (Fab)2, Positive Subcloned 1 well (PC-9F9) CD4OL, BAFF originally lost reactivity PBMC Jan. 28, 2008 4 10 2 2 Anti-IgM (Fab′)2, Positive Subcloned 2 wells: A3 CD4OL, BAFF originally (PA3-4F5, PA3-3F2) lost reactivity TNSL A Jan. 22, 2007 20 10 2 0 Anti-IgM (Fab′)2, Positive Screening discontinued: IL-4, IL6 lost week 3 fungal contamination TNSL B Mar. 26, 2007 20 10 0 0 Anti-IgM (Fab)2. Negative Screening discontinued: CD4OL, BAFF negative at week 4 TNSL C Apr. 16, 2007 22 10 0 0 Anti-IgM (Fab′)2. Negative Screening discontinued: CD4OL, BAFF negative at week 3 TNSL D Apr. 23, 2007 15 10 1 0 Anti-IgM (Fal: 02, Positive Subcloned 1 well; CD4OL, BAFF originally lost reactivity TNSL E May 14, 2007 4 4 1 2 Anti-IgM (Fab′)2, Positive Subcloned 1 well, 2 clones: CD4OL, BAFF (TE-3A10-E3A5, TE-3A10-C7F6) TNSL F Sep. 24, 2007 20 10 0 0 Anti-IgM (Fab′)2, Negative Screening discontinued: CD4OL, BAFF negative at week 3 TNSL G Nov. 19, 2007 13 10 0 0 Anti-IgM (Fab)2, Negative Screening discontinued: CD4OL, BAFF negative at week 3 TNSL H Nov. 19, 2007 12.5 10 0 0 Anti-IgM (Fab′)2, Negative Screening discontinued: CD4OL, BAFF negative at week 3 TNSL I Dec. 10, 2007 10 10 0 0 Anti-IgM (Fab.)2, Negative Screening discontinued: CD4OL, BAFF negative at week 4 TNSL J Jan. 07, 2008 11 10 2 2 Anti-IgM (Fab12, Positive Subcloned 2 wells: (TJ-1G6, TJ-1C8) CD4OL, BAFF 2 tertiary subclones underway TNSL K Jan. 14, 2008 13.5 10 0 0 Anti-IgM (Fab)2, Negative Screening discontinued: CD4OL, BAFF negative at week 3 TNSL L Feb. 01, 2008 8 10 0 0 Anti-IgM (Fab)2, Negative Screening discontinued: CD4OL, BAFF negative at week 3 TNSL M Feb, 05, 2008 17 10 2 2 Anti-IgM (Fab′)2, Positive SubcIoned 2 wells: (TM-7C2, CD4OL, BAFF originally TM-7F8) reactivity lost TNSL N Feb. 05, 2008 5 10 1 1 Anti-IgM (Fab)2 Positive Subcloned 1 well (TN-6G7) CD4OL, BAFF Isolated clone TN-6G7-7F8-2G7 TNSL 0 Feb. 06, 2008 23 10 0 0 Anti-IgM (Fab)2, Negative Screening discontinued: CD4OL, BAFF negative at week 2 TNSL P Mar. 11, 2008 27 10 1 1 Anti-IgM (Fab)2, Positive Subcloned 1 well: (TP-2C2) CD4OL, BAFF secondary subclones underway TNSL Q Mar. 18, 2008 18.8 10 0 0 Anti-IgM (Fab)2, Negative Screening discontinued: CD4OL, BAFF negative at week 2 TNSL R Mar. 31, 2008 21 10 1 1 Anti-I9M (Fab)2, Positive Subcloned 1 well; (TR-8E9) CD4OL, BAFF originally lost reactivity TNSL S Mar. 31, 2008 17 10 2 2 Anti-IgM (Fab′)2, Positive Subcloned 2 wells (TS-801, TS-1A8); CD4OL, BAFF originally lost reactivity TNSL V May 2, 2008 8 10 0 0 Anti-IgM (Fab2,′) Negative Bead assay used; CD4OL, BAFF Screening discontinued: negative at week 3 TNSL W May 14, 2008 14 10 0 0 Anti-IgM (Fab)2. Negative Screening discontinued: CD4OL, BAFF negative at week 2 TNSL X May 19, 2008 11 10 0 0 Anti-19M (Fab′)2, Negative Screening discontinued: CD4OL, BAFF negative at week 2 TNSL Z Jun. 2, 2008 12.5 10 3 3 Anti-IgM (Fab′)2, Positive Subcloned 3 wells: CD4OL, BAFF (TZ-4F12, TZ-1001, TZ-10G9) TNSL α Jun. 6, 2008 7 10 1 1 Anti-IgM (Fab′)2, Positive Subcloned 1 well: CD4OL, BAFF (TGt-6G8) TNSL β Jun. 11, 2008 11 10 0 0 Anti-IgM (Fab.)2, Negative Screening discontinued: CD4OL, BAFF negative at week 2 TNSL γ Jun. 18, 2008 12 10 TBD TBD Anti-19M (Fab)2, TBD Screening underway (Jun. 29, 2008) CD4OL, BAFF

TABLE 17 Summary of subcloning of TN-6G7 immortalized human B cells secreting antibodies reactive with H5 HA Subclone Date # of cells/ Subclone Origin/Well stage subcloned plates well Clonal Status TN-6G7 TNSL-N/ primary Mar. 5, 2008 10 500 no 3 wells identified with H5 HA reactivity: well 6G7 2C8, 808, 7F8 (3120108) TN-6G7-7F8 TNSL-N/ secondary Apr. 01, 2008 2 500 no Well 2G7 identified with H5 HA reactivity well 607 (412108) TN-607-7F8- TNSL-N/ tertiary 06110108 2 50 yes All wells identified with H5 HA reactivity 2G7 well 6G7/ (Jun. 25, 2008); Ig genes sequenced well 7F8

Characterization of TN-6G7-7F8-2G7 cells. Subtyping of IgG in culture supernatant from TN-6G7-7F8-2G7 cells indicated that the cells secreted IgG₁ (FIG. 53B). This was confirmed and further analyzed by RT-PCR analysis (FIG. 54), which indicated that the cells expressed λ1 light chain and V_(H3) heavy chain (FIG. 54B). Sequencing of the PCR amplification product indicated that the light chain immunoglobulin variable region was composed of IGLV015 and IGLJ2*01 gene segments (FIG. 55A) (SEQ ID NOS:32 and 33). The heavy chain immunoglobulin variable region was composed of IGHV318, IGHD4-23*1, and IGHJ4*3 (FIG. 55B) (SEQ ID NOS:36 and 37). While the light chain region had >99% homology to germline sequences, the heavy chain region was hypermutated with 92% V_(H) germline homology, 56% D_(H) and 80% J_(H) homology to germline; the obtained sequences compared against the germline sequences are presented in FIGS. 55A and 55B. The complentarity determining regions of the heavy and light chains are identified in FIG. 55C (SEQ ID NOS:39 and 40).

Example 7 Determination of Dissociation Constants (K_(d)) for TE-3A10-E3A5 Monoclonal Antibody by Competition ELISA

Dissociation constants are a measure of the affinity of antibody for the antigen. The lower the dissociation constant, the higher the affinity. Generally, antibodies with Kd less than 10⁻⁸ are considered in the therapeutic range. In order to calculate the antibody dissociation constant for E3A5 monoclonal antibody, the investigators needed to know the antigen-antibody complex concentration at equilibrium, the total antibody concentration, and the amount of antigen sites at equilibrium. These were then used to generate a Scatchard plot. The Scatchard equation is [x]/[Ag]=([AbT]−[x])/K_(d), where [x] and [Ag] are antibody-antigen complex and antigen concentrations at equilibrium, respectively, and [AbT] is the total antibody concentration. The investigators used the method presented by Friguet et al. (1985), where the antigen-antibody equilibrium is pre-established prior to exposure to coated antigen. If the coated antigen interacts with only a small fraction of free antibody (10% or less), it will not significantly shift the equilibrium, thus ensuring that the true affinity is being measured. The reciprocal of the affinity constant then yields the dissociation constant, K_(d), where K_(a)=1/K_(d).

Determination of the amount of antibody interacting with the coated antigen. As mentioned above, it was crucial that no more than 10% of antibody binds to antigen on the plate. To determine if that condition was met, the wells in two identical 96-well plates were coated with his-H5 HA, 100 μl per well at 500 ng/ml in DPBS, overnight at 4° C. Next day, a 2-fold dilution series of E3A5 was set up, using RPMI 1640 complete media as diluent. After the plates were washed and blocked according to standard H5 HA ELISA protocols, the antibody dilutions were placed in the wells in triplicate, 100 μl per well of plate 1 and incubated for 15 min at room temperature. Next, the contents of all the wells on plate 1 were transferred to their exact counterparts on plate 2, followed by a second 15 min incubation. Subsequently, both plates were washed and exposed for 1 hour to alkaline phosphatase-coupled goat anti-human IgG Fc detection antibody diluted 1:10,000 in blocking buffer, at 100 μl per well. Following a colorimetric substrate reaction and detection, average OD₄₀₅ values±standard deviations (n=3) were obtained and plotted against the relevant antibody concentrations. Lines were fitted to the data points, and line slopes for plate 1 (S₁) and 2 (S₂) were determined. Level of antibody binding to coated antigen was calculated by the formula S₁−S₂/S₁. A value of 0.1 or less indicates that 10% or less of the antibody bound to the antigen coating the plate.

Determination of Kd. A 96-well plate coated with H5 HA antigen was prepared as described. Solutions containing E3A5 at 18 ng/ml were prepared with complete media. His-H5 HA (75 kDa) was prepared at 10 different concentration as a serial 2-fold dilution, from 1.3×10⁻⁷ M to 1.3×10⁻¹⁰ M. Equal volumes of antibody solutions and each of the antigen dilutions were mixed together and allowed to equilibrate at room temperature overnight. The next day, the pre-incubated antibody-antigen solutions were added to washed wells of the prepared plate at 100 μl per well. Following a 15 min incubation, the rest of the steps followed the protocol described above precisely.

The following equations were utilized in making K_(d) calculations: [Ab]=[AbT] (A/A_(o)); [x]=[AbT] (A_(o)−A)/A_(o); [Ag]=[AgT]−[x]. Where A_(o) is absorbance in the absence of soluble antigen, and A is absorbance at a particular antigen concentration. A graph plotting v/[Ag] versus v, where v=[x]/[AbT] was generated. From the slope of the graph, the affinity constant, K_(a), and its reciprocal, K_(d) for E3A5, were calculated. As can be seen in FIG. 56, the average Kd calculated from two replicate plates for E3A5 binding to H5 HA was 1.625×10⁻⁹, with standard error of 3.75×10⁻¹⁰.

Example 8 Production of Full-Length Ig Chains from TE-3A10-E3A5 and -C7F6 Cells, and Construction of Recombinant Retrovirus Expression Vectors

In order to create cell lines producing the recombinant Ig genes isolated from clones E3A5 and C7F6, the full length heavy and light chain Ig genes were amplified from their cDNA. The variable regions were approximately 400 bp, while full length light chains were about 700 bp, and full length heavy chains were about 1400 bp (FIG. XXXA). In order to create the primers, a BLAST search of Genbank was performed using the cloned variable region sequences, to identify leader peptide sequences, for new primer design. Reverse primers for the C-termini of the constant regions of the heavy and light chains were derived from published sequences of those genes. The primers used were: L-VλE3 (5′AAAAAAAAGCGGCCGCCATGGAATACCTATTGCCTACGGCA3′) (SEQ ID NO:41) and L-VλC7 (5′AAAAAAAGCGGCCGCCATGGCCTGGTCTCCTCTCCTCCTC3′) (SEQ ID NO:42) in combination with reverse primer CT-Cλ (5′AAAAAAAGGATCCTAWGAR CATTCTGYAGGGGCCACTGT3′) (SEQ ID NO:43) for amplification of IgG light chains from E3A5 and C7F6 cDNAs, respectively. Similarly, L-Vh1 (5′AAAAAAGCGGCCGCCATGGAGTTTGGGCT GAGCTGGGTTTTC3′) (SEQ ID NO:44) and L-Vh3 (5′AAAAAAGCGGCCGCCATGGAGTTTGGGCTG AGCTGGCTTTTTC3′) (SEQ ID NO:45) with reverse primer CT-CIgG1 (5′AAAAAAAGGATCCTCATTTACCCRGAGACAGGGAGAGGC3′) (SEQ ID NO:46) were used to amplify the heavy chains of C7F6 and E3A5, respectively. PCR reactions were performed using the AccuPrime Taq DNA polymerase (Invitrogen, #12339-016) with the provided PCR buffer I, and with primers at the final concentration of 1 μM each.

Full length heavy and light chains from both E3A5 and C7F6 cells were isolated (FIG. 57A).

Restriction enzyme sites incorporated into the forward and reverse primers allowed for direct insertion into expression vectors. Retroviral vectors were chosen for delivery of full length E3A5 and C7F61 g genes to CHO, 293 and myeloma cell lines, because retrovirus vectors integrate into the cell's DNA, allowing for rapid establishment of stable cell lines. In order to construct the retrovirus vectors, pQCXIN retrovirus vector (Clontech) were modified by replacing the neomycin resistance gene (neo^(R)) with a gene for enhanced green fluorescence protein (EGFP) to create pQCXIG (FIG. 57B). E3A5 and C7F61 g gene PCR products were purified using Qiagen spin columns, digested overnight with EcoR1 and Not1 restriction endonucleases (in EcoR1 buffer), and ligated with retroviral expression vector plasmids also digested with EcoR1 and Not1. Light chains were inserted into pQCXIN, to generate pQC.E3A5-LC.IN and pQC.C7F6-LC.IN, while heavy chains were cloned into pQCXIG, to generate pQC.E3A5-HC.IG and pQC.C7F6-HC.IG, as described in FIG. 57B.

All of the compositions and/or methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the compositions and methods of this invention have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the compositions and/or methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit and scope of the invention. More specifically, it will be apparent that certain agents which are both chemically and physiologically related may be substituted for the agents described herein while the same or similar results would be achieved. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the appended claims.

VII. REFERENCES

The following references, to the extent that they provide exemplary procedural or other details supplementary to those set forth herein, are specifically incorporated herein by reference.

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The invention claimed is:
 1. A method of producing an immortalized human B-cell expressing an antibody specific for a predetermined antigen comprising: (a) obtaining a population of human B cells, wherein the majority of the human B cells have not undergone IgM-to-IgG immunoglobulin isotype class switching; (b) contacting said population with Epstein-Barr virus (EBV) to immortalize said human B cells; (c) contacting the human B cells with a cytokine/growth factor/signaling agent cocktail to induce IgM-to-IgG immunoglobulin isotype class switching; (d) culturing cells under conditions supporting said immortalization and immunoglobulin isotype class switching; and (e) selecting an immortalized human B cell expressing an antibody specific for said predetermined antigen.
 2. The method of claim 1, further comprising isolating a nucleic acid encoding (a) an entire antibody heavy and/or light chain from the immortalized human B cell of step (e), or (b) a heavy and/or light chain antigen-binding fragment from the immortalized human B cell of step (e).
 3. The method of claim 1, wherein selecting comprises an immunoassay performed on immortalized B cell culture medium.
 4. The method of claim 1, wherein said contacting in step (b) further comprises use of concentrated EBV or use of a centrifugation step.
 5. The method of claim 4, wherein step (b) further comprises use of concentrated EBV and use of a centrifugation step.
 6. The method of claim 5, wherein about 95-99% of the B cell population are immortalized by EBV infection.
 7. The method of claim 5, wherein EBV is concentrated 10-fold and wherein centrifugation is performed at 900×G for 1 hour.
 8. The method of claim 7, wherein about 95-99% of the B cell population are immortalized by EBV infection.
 9. The method of claim 1, wherein step (b) further comprises contacting said B cells with toll like receptor ligands.
 10. The method of claim 1, wherein said cytokine/growth factor/signaling agent cocktail comprises one or more of anti-IgM F(ab′)2 or other agents that crosslink or activate B cell receptor, soluble CD40L, recombinant human IL-4, IL-5, IL-6, IL-9, IL-10, IL-13, INF-α2a, BAFF, or other cytokines that cause B cell differentiation.
 11. The method of claim 1, Wherein said cytokine/growth factor/signaling agent cocktail comprise's (a) anti-IgM F(ab′)2, CD40L+/−BAFF; (b) anti-IgM F(ab′)2 and BAFF; (c) CD40L+/−BAFF; (d) anti-IgM F(ab′)2 and IL-6+/−IL-4; or (e) anti-IgM F(ab′)2 and IL-9+/−IL-13.
 12. The method of claim 1, wherein step (c) is performed at about 0-96 hours following step (h).
 13. The method of claim 1, wherein step (c) is performed at about 16-20 hours following step (b).
 14. The method of claim 1, wherein step (c) is performed two, three, four, or five times at approximately weekly intervals.
 15. The method of claim 1, wherein step (e) occurs about 1-4 weeks following EBV infection.
 16. The method of claim 1, wherein step (e) occurs about 2-3 weeks following EBV infection.
 17. The method of claim 1, further comprising freezing said population of human B cells following step (d).
 18. The method of claim 17, wherein step (e) occurs after thawing stored frozen immortalized B cells, and/or after thawing stored frozen culture medium supernatants from said immortalized B cells.
 19. The method of claim 1, wherein said predetermined antigen comprises a viral antigen, a bacterial antigen, a fungal antigen, a parasite antigen, a toxin antigen, a cellular receptor antigen for virus entry, a cellular receptor for bacterial entry, a cellular receptor for fungus entry, a cellular receptor mediating parasite entry, a cellular receptor mediating toxin entry, a tumor antigen, a cytokine/chemokine/growth factor receptor antigen, an antigen on molecules mediating inflammation, an antigen on molecules mediating pain, an antigen on molecules mediating tissue injury/damage, an antigen on activation molecules/ligands/receptors, an antigen on molecules mediating innate immunity, an antigen on cellular adhesion molecules, an antigen on cellular adhesion molecule receptors, an antigen on over-expressed/under-glycosylated/oxidized/misfolded/mutated cellular proteins (“altered self” antigens) associated with a disease state, an antigen on molecules/ligands/receptors mediating cell apoptosis, an antigen on growth inhibitory molecules, H5N1 hemagglutinin (H5 HA), cancer angiogenic molecular placenta induced growth factor (PLGF), cancer and autoimmunity associated factor interleukin-6 (IL6), Staphylococcal enterotoxins B (SEB), Staphylococcal enterotoxins C2 (SEC2), or ricin subunit B.
 20. The method of claim 1, wherein said population of human B cells is obtained from tonsils, peripheral blood, bone marrow, spleen, lymph nodes, umbilical cord blood, liver, apherisis procedures, and/or buffy coats.
 21. The method of claim 1, wherein the human B cells obtained in step (a) have one or more of the following characteristics: a) a large portion of said population of human B cells are IgD-positive; b) said population of human B cells are mostly naïve; c) the human B cells in step (c) are induced to switch from higher level of IgM secretion to higher level of IgG secretion; d) said population of human B cells is obtained from a subject not previously exposed to said predetermined antigen; e) said population of human B cells demonstrate increased CD2O expression as compared to a mature population of human B cells; f) a large portion of said population of human B cells demonstrate low level expression of a marker selected from the group consisting of CD27, CD30 and CD38; and g) the majority of said population of human B cells have not undergone somatic hypermutation.
 22. The method of claim 1, wherein said antibody is monoclonal.
 23. A method of producing a B cell repertoire expressing an antibody specific for a predetermined antigen comprising: (a) obtaining a population of human B cells, wherein the majority of the human B cells have not undergone IgM-to-IgG immunoglobulin isotype class switching; (b) contacting said population with Epstein-Barr virus (EBV) to immortalize said human B cells; (c) contacting the human B cells with a cytokine/growth factor/signaling agent cocktail to induce IgM-to-IgG immunoglobulin isotype class switching; (d) culturing cells under conditions supporting said immortalization and immunoglohulin isotype class switching. 